Good points.
I look at it from the perspective that Gears (and the Forza 2 ad) seem to do a good job of selling games. But do they do a good job of moving consoles? Part of the appeal of the 360 this Fall should be the fact that it has tons and tons of great games. From Madden to the NBA games, to the NHL games, to Rock Band, to Guitar Hero 3, to FlatOut, to COD4, to GTA IV, to Mass Effect, to Halo 3, to Assassin's Creed, to Orange Box, to Left 4 Dead, etc. etc. etc. Nevermind the Live titles...
The last time MS tried to sell the concept of "we got lots of games on our console"...we saw an ad of green DVD cases stacking up with various game sound effects. It made no sense to non-gamers, and it wasn't particularly convincing to gamers. Now, I realize that E3 had a montage of gameplay and that was equally boring, and that was because it was set to music and no narration.
Compare that to Sony's ads. They show the game, good amounts of gameplay (that is impressive to both gamers and non-gamers), and then show the actual console with the controller.
This is a highly subjective topic so I'll shut up now. I just don't think MS can advertise. Can't really do a good job of creating hype, and despite having a killer game lineup, I don't think they have what it takes to sell the console to gamers who have yet to take the next gen plunge.