I went from 'let's take this place over!' to 'screw it' in about two days: the days after popularity sort was implemented. The only way you can emerge from the sea of thousands of maps is by spamvertising on the forums and even then a lot depends on dumb luck.
I'm not too lazy to learn the editor. The harder the better, it keeps competition down. Diablo 2 is very hard to mod and I'm the king, getting into the top 10 mods of the year at ModDB in 2009. However, Diablo 2 has a significant single player community which enables people to recommend the mod to each other and get the snowball rolling, whereas if a multiplayer SC2 map is dead you won't sit there in the lobby and wait for some other lost soul to join it.
I will not invest months of my time into a map that is dead by default unless I get lucky. I'm not retarded;
Also, SC2 was a bit of a commercial failure. It appears Dota-like games (League of Legends, Heroes of Newerth) have taken over from old school strategy games, just like RPGs displaced adventure games.