Alright, I know that sounds a bit pedantic, and I do recognize the difference in tone between "repetition" and "repetitive." Lack of variety is a fair criticism, but "too repetitive" is an extremely vague way to say it, and it dodges the truth: when we criticize a game for being "too repetitive," I think we often mean that we just don't like what we're doing. "It's repetitive" is shorthand for "this isn't fun (for some reason)."
If we like what we're doing, repetition is desirable. I like solving puzzles in Portal, and once I solve one I want to solve more. I don't want to solve the exact same puzzle again, but I don't want to stumble into a surprise Sudoku chamber, either. So Portal gives me increasingly clever arrangements of portal-ey logic problems. The puzzles get harder, but they're all just iterations of the same basic spatial problem I solved in the first puzzle. So after all my twisty, knotty figuring arrives at a solution, it always seems just as simple as the first time. That sense of clarity comes from repetition.
Repetition is also how we learn, and both Super Meat Boy and Hotline Miami succeed by embracing that power. They present problems in small chunks—a level in Super Meat Boy and a floor of thugs in Hotline Miami—and rapidly reset them every time we fail. Each attempt gives us new information to apply to the next, building layers of experience on the way to that one perfect run. And that perfect run feels good: it's an accomplishment, like unknotting an especially tricky puzzle in Portal. Except in Hotline Miami there's more brain-stuff and skull chunks lying around afterward.
The same goes for Counter-Strike, StarCraft, and the rest. At their most basic levels, they're about repeating and mutating input patterns to solve variable, but not totally unpredictable, problems. The variables in Counter-Strike, for example, are the guns, maps, and opponents. That's been enough variety to keep us repetitively shooting at each other for 13 years.
Repetition can be pretty damn fun, so we've got to be specific, and always ask ourselves if it's really the repetition of a theme that bothers us, or the theme itself. I can shoot bad guys all day, so complaining that "the shooting is repetitive" in Medal of Honor: Warfighter would be confusing. Further examination would reveal that the guns, maps, and enemies have specific traits I don't like, which has nothing to do with repetition (except that the more I do them, the less I like them).
Fearing the dreaded "repetitiveness" may even be bad for games: that's probably how we end up with off-key phrases at pivotal moments, like a boss fight which takes away the gun I've been using the whole time and sticks me in a surprise platformer. It's variety, but it screws up the whole composition. A performance of Rachmaninov's Piano Concerto No. 2, for example, would not benefit from an unexpected dubstep interlude. No, I wasn't talking to you, Skrillex. Are you drunk? Go home, dude.
Anyway, if at first glance this looks like an ostentatious rant about a personal pet-peeve, then you may have seen correctly. But maybe not: try Googling any game name with the phrase "too repetitive." It's everywhere. I get what's meant by it (sort of, kind of, some of the time), but it says very little. It may not even be a criticism, because games like Hotline Miami wouldn't be fun without repetition. If dying and respawning didn't reset the level, and our prior kills stayed bloodied, it would be ruined. Maybe then we'd say that it's not repetitive enough?