People talk about step-g like it was a bad thing, but I'm telling you right now that SC2 is a far higher level game than SC 3 4 or 5 ever was. Way faster too.
SC2 was more akin to a physical sport with the speed you had to deal with. In SCV they were almost back to returning the series to that glory, but when Daishi decided to make movement unsafe as all hell in the patch you pretty much had to throw that out the window entirely and just guess.
There is nothing wrong with a 5-move-game. It means you have 5 moves that are clearly really fucking good, which is roughly 4 more moves than the average fighting game character gets anymore. The reason SC2 was so accessible is because its easy for anyone to pick up a character and learn their 5 best moves, and when to use them.
Yes, it was simple, but so what? It was fun, it worked, the pacing was unmatched and damn near anyone could play the game.