Copycat Game Design
Perpetrators: Gameloft, Zynga
Worst Example: Dungeon Hunter: Alliance
Money may be money, and creativity may be expensive, but the absolute lack of creativity that fuels companies like Gameloft is outright despicable. Seriously, when a majority of your company's library are two-bit clones of more popular, better designed games, you'll eventually hit a point where consumers just won't put up with your cut-rate crap anymore.
This gets even more problematic when you extend this notion to the triple-A world. Developers have been pilfering mechanics from each other for decades, and there's nothing inherently wrong with that, but stealing things like tone and narrative structure makes the entire marketplace a blur of samey garbage.
The Solution: Stop riding coattails and make something original