>The per-process 'hard' limit should be a fixed number.... say 1024.

Uh... I have applications which run with 6,000 to 10,000 open fds in a
single process. I don't want to allow any random process or user to
open that many fds.

We (collectively) a habit of reasoning along the lines of:

   ``Right now I, personally see no use for feature X;
     therefore there *is* no use for feature X''

The pitfalls in that approach should be obvious.