I am playing 0.3.0 because I like it. I don't like other versions.
Er... why?
0.3.0 was a long time ago, but it was still long enough after 0.1.3 to have incorporated most of be really big changes for Milestone 2. The only possible things I can think of that 0.3.0 has that 0.4.x and later don't are the forest world, Tux losing his fire powerup any time he backflips, and the (in my opinion) absurdly large number of (not very good) music tracks. The forest thing is kind of minor since it still exists as a bonus level last time I checked, the backflip thing I don't see any reason to prefer, and the music thing only showed up with... was it 0.3.4? So you don't need to go
that far back.
In any case, what you're going to have to realize is that when someone is developing a game, they don't really have the time or inclination to support old prerelease versions of the game, which is what 0.3.0 was. If you disagree with recent design decisions, I recommend you fork SuperTux and make changes to bring back what you liked from older versions, then maintain that. This is something you have freedom to do since SuperTux is libre.
You can even take the old codebase from 0.3.0 and fork that if you really want to.