Yeah I think SSE is criticized much too heavily given the circumstances. If they were ever gonna do an expansive story mode, that was the time, when the roster was getting big enough that it would actually come off as a huge deal but not so big as to cause concerns that it might be completely untenable. The story is mostly an excuse for some fun interactions between characters, with enough lore stuff to keep it interesting. That format of "get some small groups of characters together to generate those fun interactions and then have them all team up against the big bad at the end" is basic, but ultimately just about the only way I can think to formulate that kind of crossover story in this kind of medium effectively. Add in the way you have to juggle so many IPs and please the multiple parties involved, and the outcome was about as good as could be expected. Could the level design, enemies, and exploration aspects have been improved? Yes, and I'm not saying the mode should go without any criticism at all, but it's still very solid what they were able to accomplish all the way back in 08.