2) What _exactly_ is the use case?
3) If you can install non-posix tools, why not use a full-featured file manager? And if there is no use-case for a program, why am I installing more custom software on my system. ls is already installed, you still have to convince me that installing a less portable version of ls is worth more than the trouble of an additional dependency
P.S. regarding 3, I would not point this out if you had not claimed my post was "Some strawman arguments", but: your 3) is an actual strawman argument. You have created a strawman version of me that you are hinting only uses POSIX programs.
P.P.S. there is a real feature that would be useful for an ls-like program, which is listing directories with a huge number of files. Standard implementations of ls cannot handle reading directories with millions of files (even though the filesystem could) because of a misconfigured buffer size: http://be-n.com/spw/you-can-list-a-million-files-in-a-direct...
1) if it works it works. I guess most people use a small set of terminals these days (ie 80% of users probably use 20% or less of terminals)
2) can just use ls if needed. The tool does not need to be a superset to be useful
3) most people use these on a few devices they own and where they can install non-posix tools. Are all programs you use posix? Seems wild