Thanks for the many responses. I'm hearing consensus that I'm being way too cautious, but probably not hurting myself much since minor piety loss is the only real drawback.
Also, I love that the subject lines of all the replies have been truncated to "...a waste of tim" -- poor Tim.
TheDefiniteArticle wrote:This is totally useful, and in the case of launchers should be done almost obsessively.
Glad you brought up the issue of launchers, I find that crossbows of flame/freezing will almost always get scooped up by certain enemies, e.g. orc warriors and yaktaurs. But by this logic it would also be a good idea to grab all branded ammo, and that really does seem like too much work. And if you have Cons/Pres it's not a big deal.
I think going forward I'll adopt a policy of:
- in very early D, grabbing any randart weapons just to be on the safe side
- after D:3 or so, only grabbing weapons that have been IDed through combat to have a worrisome combo of brand & base type, and dumping them in corners or one floor up (except Distortion or other unreasonably dangerous things)