The big serve (Roddick, Raonic, Karlovic, etc.) Most of the players who have a big serve have very little else. At times, the high mileage serve winds up being a giant error.
You're kind of digging yourself into a logical hole here. You're listing the big serve of various players as an overrated shot, and then claiming that these same players have very little else to offer. You're essentially saying they win tennis matches with scraps, which is an especially questionable claim sgainst someone as accomplished and proven as Roddick...
Also, I'm not sure anyone overrates Karlovic's serve. Most people know what he brings to the table, and the most you'll *usually* hear about him is, "He can be tricky", or "Guys don't want his name in the draw", or "He can force a tiebreak". I really don't see any of that as out of line.
I agree with those who have mentioned Nadal's volleying. That's not to say it isn't respectable, but it's not what people make out to be, and I'd take it a step further by saying he doesn't do it enough to consider it a real factor.