I think this has more to do with the forum hoster and not you (Lucky/fucking faggot), but I have 2 problems with the avatar system. First and less importantly, they could be a bit bigger. Nothing too big, but 300x300 seems fair. More importantly though, I was surprised to find that the forum does not automatically resize images bigger than 100x100, as it is pretty standard for most forums and it's necessary for a lot of the better avatars. If there is a way to increase the avatar restrictions and, more preferably, include image resizing, I'd be very grateful. Code: Please do not use blanket color --fucking faggot
In answer to your question no there is little chance at the moment of the avatar size being increased, the reason being is that we would like to conserve space on the system where possible, 100px is simply large enough. As for Avatar resizing that is not an out of the box feature and while it may be added in the future at least for now opening up paint and resizing your image is not too much of an issue.
I can understand that you want bigger avatars, but 300x300 is overkill, IMO. 200x200 is the maximum size I can tolerate. 150x150 should be enough, but leaving it at 100x100 is fine too.