Your argument for this is basically "I'd rather have covers with credits on them then no covers at all, you can photoshop the credits out if you're really that bothered by it".
My viewpoint is multi-fold.
1) Yes, a lot of it boils down to the fact I'd rather have covers with credits than no covers at all. Yes, of you're bothered by it, you can either photoshop it out (you still get a cover out of it) or just not print it at all (and then you're no worse off than you were beforehand).
2) There are some folks who put a lot of work into their covers - and it shows. If
they want to put a credit on the cover, then
I don't mind. It's a very minor thing, in my humble opinion, that doesn't take away from the overall quality of the cover and I don't feel right dictating to them that they cannot take credit for their work.
3) Ultimately, no one is being FORCED to sign their work - it's still up to the individual cover artists, of which all who have responded said they have no intentions of signing their work. However, the fact that we're giving the artists a
choice is something that errs on the side of caution.
Is this me thinking my views on this should dictate site policy? Well sure, me and every single person who's posted in this thread besides you.
I used quotes around the 'you' for a reason.

And you are correct - I appear to be the only one really siding with the view point of allowing an artist to take credit on their work if they so wish. While I find that a little sad, that is the purpose of this thread - so that we can discuss it and see how the community feels about it to determine if there is a consensus towards making it an official rule.
However allowing crediting for special cases such as use of someone else's artwork for a custom cover would give more options and possibilities for great covers. There are far more artists out there than there are cover makers. And far less cover makers who have enough artistic talent to make a great custom cover based on their own artwork.
Great points.