Yes, it's possible to move to ~/.Trash or something -- but now you need to write ever-increasingly-complicated scripts to e.g. unrm a directory tree.
I agree that backups are necessary, but who hasn't had a corrupted backup? And it's much less convenient. With disks so big these days, a 'shadow filesystem' seems most logical to me.
Heck, if you think about it, this is precisely what VCSs like git or subversion do -- they give you 'infinite undelete'. I'm just saying, gee, isn't that a grand idea --- shouldn't we do that for ALL files, by default?