I'm guessing the vocal appeals to the masses. Including a good portion of the "real" trance listeners, and not only the "casual" ones. It's a guilty pleasure for quite some of us, with that overemotional over-the-top vocal. But secretly it's fun.
Same as with Concrete Angel. If you sing along that track in a club, it's sort of funny. It's so over the top...
What also helps, is that a lot of Gareth Emery releases have a poppy 'original', and they include a "Joc" or "Kearney"-esque name for a pretty generic but fine uplifting remix, that get's hammered by Armin.
Gareth Emery is still huge though. Don't see why it just would be "early 2010". He recently had another Tune of the Year with Saving Light (which follows the same guidelines as the others...).