i don't think we want to turn off signatures en masse, i think they add some nice flavor, and like tinjaw says, anyone who doesnt want to see any signatures can easily turn them all off.
this isn't a big deal, just something we might be able to improve a little with some suggested guidelines.
and you know we can't help tinkering with things here and discussing the "best" solution to any given problem
the other alternate solution that i think might be a nice little forum modification that let users enable and disable specific user's signatures in an easy way, with the ability to mark certain users signatures as disabled by default. like just a little + or - button to the left of a signature that collapses it to 1 line hight, and the setting would be remembered forever, so once you collapse someones signature it will remain collapsed *for you* on every post they make until you expand it again, and vice versa. i just don't know if that's not overkill.