And you talk about COD's mechanics like they are a bad thing, considering how many people play COD online in comparison to this mod I would have thought you would have chosen your words more wisely. The "Mechanics" are the difference between a good online game and a bad online game, so with that in mind I can only assume that with the sheer enormity of people playing COD online, Activision must have got it right.
This is pure ignorance. Lets dissect:
Comparing how many people play a Triple-A title game on multiple platforms with an entire dedicated game design studio behind it with a budget ranging in the millions for things like advertising, voice acting, special effects etc... to a mod developed for no money in people's free time who's playerbase consists solely of people who are interested enough in mods to try them, own a source game/or are prepared to buy one, meet the system requirements, use Steam etc...
Popularity has so little to do with game mechanics, particularly in the case of Call of Duty which is a successful series that has been running for almost a decade. There could be a CoD title that used identical mechanics to GE:S and it would still have millions of players simply because it's a CoD title.
Fact is the vast majority of players are easily pleased and aren't capable of thinking critically. They aren't even aware of what game mechanics are being employed and aren't clued enough to realise if these are good or bad.
And none of this implies that anyone thinks CoD is bad. In fact I think CoD is very good, it does what it does well and it satisfies the main-stream market. Main-stream consumers are virtually conditioned to stick to particular brands, titles, genres, whatever you call it, and it's only the minority who break away and are actually open minded or analytical to try the unusual and the obscure, and not all of those are prepared to climb the learning curve and patiently improve themselves.