The reason for stubby domination is that they haven't really had a great deal of time to balance the game because they've been trying to overcome technical barriers. You'll notice that MTA:VC has changed significantly in the technical department over the course of its existence whilst gameplay has had only minor changes.
In 0.4.x they mainly concentrated on GTA3, as that was in need of an overhaul. Stunt mode wasn't even going to be included, but they got it working at the last minute. This is why there were no major changes to it. MrBump has posted a topic somewhere in the forum asking people where they would like ramps to be placed, implying that they will be focusing some of their 0.4.2 development time on stunt mode.
Regarding the fire truck, that's probably possible with Blue.
They're planning to include several new game modes with the release of Blue. They may make a Cops and Robbers mode but if not, it's easy enough to create your own (or wait for someone else to). I doubt they will do this for 0.4. NPC cops are highly unlikely too.