I agree that there does need to be restrictions on sigs to only static images - some of those animated gif sigs some people have really lag forum pages down when they're trying to load - not all of us have super fast (or reliable) internet sadly.

I disagree with only allowing sigs to be text however (my own 1.0-themed sig is quite small in size and doesn't waste much bandwith). Ultimately it's SE's decision though.