I don't claim to understand the techical side of things, but I have to imagine that some of the larger signatures use a lot of bandwidth/space (??) and add to the expense of running the forum.
I don't claim to know what I'm talking about here either, but I believe if the signature pics are linked from a site like Photobucket, that they don't use up bandwidth/space here.
As for my opinion on this thread topic.. I enjoy seeing everyone's signatures and don't even mind if they are somewhat larger (like my size, or Ambesi's, or MssJnnfer's) There are just some that use several pictures that take several scroll's to move past that its somewhat annoying. Even if they put multiple pictures ACROSS, instead of up and down, that would make a huge difference.
But I don't really care. If it stays the same, I'll deal with it. I'd actually prefer there not to be a set max by the forum, as on most other forums I've been on that have a set max, its TINY!!