I've noticed a disturbing trend recently, first at a panel at GenCon, then again here on the forums:
Lack of imagination in DMs.
Dungeons & Dragons is a game of imagination. That phrase gets bandied about a lot, of course, but it's true and it's worth analyzing a bit. D&D is played primarily in the imagination. The minis are just representations of the characters; the mechanics are just abstractions of the characters' bodies and minds. The game actually takes place inside the mind of each person sitting around the table.
Which is why I get confused at DMs complaining because certain abilities can be combined to, theoretically, deal unexpectedly large amounts of damage in certain circumstances. The implication is that this "breaks the game."
If the players are dealing so much damage that they're easily killing monsters, make the monsters harder. Increase their HP. Give the monsters special abilities. Introduce higher-level monsters.
The only thing that can truly break D&D is a lack of imagination.