[jaen]

Explicit stack-based interfaces are used for good reason: This allows simple accurate garbage collection (see eg. the Ruby API which requires somewhat error-prone conservative GC, Python which requires refcounts all over the place, or OCaml which requires annotating all local variables in a special block). A custom frame stack is also needed to have coroutines in pure ANSI C (two of the reasons Lua is popular).

[sesquipedalian]

I don't believe non-stack based APIs prevent the implementation of the features you just mentioned. You don't necessarily have to expose the underlying stack manipulation routines as your defacto API although it is easier to do so. My gripe with this technique is that it makes it much harder for the compiler to catch errors. Personally, I think it would be better to expose the API as helper functions that compose (and hide) the underlying stack routines.