I must admit I'm against limiting the number of images in a post or making people have to thumbnail them if they were over a predetermined size from the standpoint that it'd make having display a large number of reference pictures even harder to display online. Having things remain as they are now might cause a minor inconvenience for some, but if it gets problematic the Mods can simply edit a person's post and cut down the number of images, and there hasn't really been enough to suggest we need such restrictions put into action.
I know from my own experience as well as that from others that it's irritating to have to click on every single thumbnail if there's several dozen images just so I can save the full size image of each thumbnail. It also means if someone's doing a poster of their story or team, if it's over a certain size then it has to be thumbnailed, defeating the point of it… and that was a decision I didn't like when it was implemented on Troy's board.
And if the number of images were limited, it'd make something like the collation of Firehouse images for a Firehouse model project on Proptopia pretty much impossible.
I'm also against increasing the size allocation for avatars, they're perfectly fine at the size allocation they're at now.
And as it stands, there already is a Split Topic option, but it's reserved for Moderators and Admin only.