Heck - at this point, resource forks are exposed as a "com.apple.ResourceFork" xattr with a large binary value. The primary remaining visible quirk is that they're also accessible via a magic path ("file/..namedFork/rsrc") -- the fact that the file system has a special way of storing them is irrelevent to userspace.
yah absolutely ext4 has progressively had its' performance reduced because what made it faster than ext3 created a lot of corner cases that make it far less reliable, and Btrfs is at least a fresh design, but doesn't seem to be particularly ready and is not even proven as a reliable design.
It's good that we have more than one filesystem. HFS+ functionally works well for a Mac because the Mac is designed around it, but it is part of the reason that OSX falls short as a UNIX at times.
> what made it faster than ext3 created a lot of corner cases that make it far less reliable
That is an odd claim, considering that the ext3 implementation has been removed from the kernel this year, and various distributions have for several years already used the ext4 driver to mount ext3 filesystems.
Yes it is likely that ext4's days a numbered in terms of developing new features, however _today_ it is still the best choice for a filesystem if you don't run a bleeding edge kernel, and don't need the extra features. BTRFS is seen as the next defacto standard linux filesystem, and it has a ways to go before it can match the performance of ext4.
http://manpages.ubuntu.com/manpages/precise/man5/attr.5.html