XiaoChanLung, you are missing the point entirely.
You are quite right. They can set up any rules they want to. These are THEIR forums, not ours. The rules they set up are fine, in principle. What I want are specific rules. I don't want them to say "use your own judgement" on forum signatures. I want a specific rule "max 100x500" (or whatever).
I think we can all agree that very few of us ever post anything that *we* consider to be out of place, or bad (non-trolls anyway). If we do so, we don't mind if it gets deleted. But if we post something normal, and it gets changed, we get mighty ticked off (or at least I do. And apparently so does Kumu).
Why is this important? Well, lets just consider a scenario for a moment:
Let us say that I create a signature. It is 250x700 (I've seen siggys easily that big before on unmodded forums. In fact, I've seen siggys that were the size of a sheet of A4 paper, but that's just silly). Lets say I put in... 3 hours to photoshopping this siggy, and I'm pretty proud of it.
I put it on the forum, and it gets deleted, with the explanation that it was too big. At first I'm kind of angry, but then I shrug my shoulders and move on. Whatever, it was too big. Because of the way this particular siggy is put together, I can't just shrink it, cause it will ruin it (lots of siggys are like that, especially if they have text). So I go and I spend another three hours creating a new siggy. I was told to just use my own judgement since this forum has no set and fast rules, so I make this one is 175x500. It looks really cool to me, and I'm happy with it. In fact, I'm kind of glad my first one was removed, cause this one is even better.
I go back onto the forums, and I place my new siggy. It gets deleted. Opps. Turns out the mods will delete anything bigger than 100x400, but they refuse to tell me that fact, instead telling me to use my own judgement again. At this point I am so freaking ticked that I cancel my accounts, pick up my ball, and go leave. I think to myself: "I put six hours into those siggys, and they CAN'T EVEN BOTHER TO TELL ME WHAT SIZE I AM ALLOWED TO USE!"
And all that could have been avoided by giving a specific rule. Easy peasy. This WILL happen if they don't create hard rules. It isn't a matter of if, it is a matter of when. Oh look. It already happened. That's why this thread is here.