srgs
3DS FC: 0430-8596-8893
Towns Folk
I don't know if you know how it works, but sprites are done frame-by-frame. Sprites, like 3D models, must be built up from scratch, but unlike 3D animation, animating sprites takes longer, as you don't have access to rigging and pose-able joints(in SSF2's case at least). Also, keep in mind that this is a small fan-game made by a small team of developers who have busy lives, not a huge team like Nintendo has.
I'm not dissing SSB4 here, as I will be getting it. But what I'm trying to say is that SSF2 is really well-made for a fan-game. The conclusions you jumped to were quite inconsiderate, seeing as you haven't even tried out the game(the first Smash Flash was terrible, don't use that as a factor to it). Like Dragovian stated, there is balancing and online multiplayer(coming very soon).