The biggest thing that is still in the language that they should have removed early on is the native XML syntax support. If I were them I would take it out in 3.0 and break from that bad decision.
Summary: No. At the time that Scala was started, built-in support for XML showcased one area were object-oriented decomposition failed and functional programming proved quite useful. Today the benefits of FP are more well known, and it's generally agreed that if Scala were starting from scratch it would not include XML literals. However, given that XML literals are in the language already, that large code bases have come to rely on them, and that they generally don't get in the way if you don't use them, it's unlikely that they will be removed.
This is hard because Scala's XML support affects the parser. At the lexical level. Scala does have compiler plugins, but it doesn't have parser plugins.
To reiterate a point implied by other commenters: macro-expansion is a compile-time operation. If the language utilizes a typing system to help promote sound programming then the results of the expansion will be compiled in the context of type constraints - the expansion is either sound or unsound w.r.t. such constraints.
To some extent there is a continuing popular schism with the idea that "strongly typed" must be synonymous with the lack of "eval", which, at least in principle, cannot be true. In fact, StandardML does have the ability to extend the environment of a program at run-time (as well as Typed Racket). All the necessary typing and meta-data is retained at run-time so that newly evaluated code is checked for type-consistency just like when the "main code" was compiled. So, not only can one expand macros at compile time and verify that the expansions are sound, one can also do the same at run-time.
I used to agree, until I ran into a bunch of inline StringBuilder Java XML where no schema existed, and simply converting it to Scala at least ensured it was well-formed while we reverse-engineered a schema. I agree it's not something one should use much (well, maybe with Lift), but wow, is it ever useful when it's useful. I agree, doesn't hurt much; helps massively when you need it.
There are several decent Scala-esque alternatives to the built-in XML support (with has many things broken about it). For instance: Anti-XML http://anti-xml.org/ and Scala-Scales: http://code.google.com/p/scala-scales/ they can't replace the functionality of the built-in support (need to alter parser/compiler for that), but are considerably more sane than the default functionality in scala.xml
Putting XML literals in the language just feels wrong. On the other hand, they've turned out to be damn useful when you're writing the back end for a web application.
It was a mistake. A better effort would have been to implement a first-class Macro system a-la Lisp. You can see here that Nemerle supports macros and makes dealing with XML like relatively painless as if it were built in: http://nemerle.org/About/#ID0E6G
I'm curious how much you've actually used Haskell's templating system.
It is my understanding that a good macro system in a statically typed langauge is still an open research problem. I remember hearing that the Racket research group was still working on it for their typed Racket system, and that it was, at least as of a year ago, not possible to directly port macros from the standard language over to the typed language.
I also remember hearing that template Haskell is a relatively primitive macro system that very few Haskell developers currently actually use, but I'm not an expert in this area.
Scala is already cutting edge in a lot of ways. Expecting them to innovate in such a difficult and untrodden area on top of what they've already done is asking a little much, especially considering that it is meant to be a practical and not a research language.
Re: Template-Haskell - sadly not enough. I have used it to generate N-tuple-generalizations of functions in toys. I simply don't get enough time to hack around in Haskell. As far as being primitive, I guess you would have to compare that to the drudgery of emitting all the automatically generated code produced by macro expansions by hand. Yes, in Haskell TH is relatively infrequently used.
In no way am I trivializing the complexity of what would be involved in bringing a useful macro system to Scala, but compiler plugins for Scala are filling this role today, a good macro system could make meta programming more accessible. Already there are plugins for SBT to invoke FreeMarker on Scala-program templates to generate code, clearly a poor-man's solution, but it simply is more evidence that a macro-system would and would be put to good use were one available.
Taking Racket as an example, a good macro system would enable many kinds of experimentation in the Scala language without having to extend the core directly. In Typed Racket Hindley-Milner type-inference was added on-top of a dynamically typed-core, and Typed Racket targets Haskell-level (or better) typing infrastructure. All this enabled essentially due to support of Macros.
RE: Cutting edge - And Haskell isn't? While there are a number of language features where Scala may in fact outshine Haskell, I would hardly place Haskell in the old and well-trodden place on the programming language landscape. It is still evolving rapidly, and without the need to conform to any particular run-time-system (e.g. the JVM) the researchers working on Haskell are able to practically make the language warp space-time.
This comment on Typed Racket isn't correct. Lots of macros work just fine in Typed Racket, and XML literals would certainly be among them [1]. The macros that don't work yet are the most complex ones, like the one implementing an entire class system with Java and Beta style inheritance (both!).
[1] In Racket, we typically use s-expressions rather than XML literals.
Disagree. Scala's syntax is already complex enough and flexible enough to all but eliminate the need for macros. XML literals were a marketing gimmick. More conventional XML support in a library would have been adequate.
Interesting. This is a common perception but not an easily justified one. A macro-system a-la Lisp (or Nemerle) could easily replace compiler plugins, and there is an active compiler plugin community so extensions to the compiler are desirable. As someone who writes in Scala every day for a living and have used the built-in XML support here and there I do not consider Scala syntax to be complex, but the XML support is ~eh~.
Despite limitations and warts it's a pretty nice language to code in on a daily basis if you're going to code on the JVM. Macros would definitely enhance Scala's productivity. If you don't like them don't use them. Certainly doesn't mean that others could not put such a tool to good use.
That's the problem with macros. It's hard enough to read Scala code as it is if the author wants to be clever. Throw in macros and it's game over. In languages with relatively inflexible or primitive syntaxes macros are a blessing but I think they're unnecessary in Scala.
Summary: No. At the time that Scala was started, built-in support for XML showcased one area were object-oriented decomposition failed and functional programming proved quite useful. Today the benefits of FP are more well known, and it's generally agreed that if Scala were starting from scratch it would not include XML literals. However, given that XML literals are in the language already, that large code bases have come to rely on them, and that they generally don't get in the way if you don't use them, it's unlikely that they will be removed.