This is to address the extreme fallacy that to be successful a game must share little to nothing in common with any other game, let alone within its genre.
There are two reasons it's a fallacy. The first is that to begin with there are far more things in common between any two games than most common players realize. The second is that while there may be an astronomical number of potential ideas that will be possible throughout time and space, only the most infinitesimal fraction of them will EVER be viable if one day the circumstances happen to be appropriate.
It's better to have a "new" game that has only some or a few minor differences from its predecessors as long as the majority of such are notable improvements, than to put out a "new" game that has been radically changed from previous incarnations for no other reason than to induce change. Change in response to a specific need is good, change for the sake of change is bad. A massive mistake that nearly all developers make is to rework the game from scratch in principle when new technology allows for new game and graphic engines. Rather than using their new capacity to develop something that utilizes the best of what made the original great with a system that can do even more, they scrap it all and try to cram as much as possible into the capabilities of the new technology just for the sake of using it all whether it's beneficial or not. You can only reinvent the genre or the industry so many times before there will simply never ever be anything different ever again (if you want it to be recognizably viable, anyway), period.
THAT is a primary reason why so many studios and publishers have put out such poor quality games in recent years. Attempts to appeal to an overly broad market are secondary, and simple mismanagement is tertiary, though all three compound one another.
Appealing to an overly broad audience means that fewer and fewer ideas are viable. The bigger the group that has to enjoy it equally, the fewer the options available to work with. This leads to an even deeper sense of repetitive production and "cookie cutter" game development. While it's not a bad thing though to appeal to a broad audience, it simply shouldn't come at the expense of placating a smaller and more sophisticated audience.
An additional problem is IP law. It's a serious obstacle to the growth and improvement of the industry when one can't take the opportunity to use a pre-existing terrible, mediocre, or even great idea and incorporate improvements of their own into a new but similar version. In tabletop RPGs, Wizards of the Coast and White Wolf are most infamous for this with their OGL and GSL and other licenses.
Ultimately though, if a game doesn't feel "new" enough or "unique" enough for you...then it's somewhat more likely that you are the problem, not necessarily the game in most instances. Supreme Commander 2 doesn't quite live up to its predecessors, and it certainly hasn't reset the bar for games period or games of its genre, but it's still a good game. It plays well, looks good, and overall is an enjoyable experience. There are many things I criticize about it, but it's the overall experience that matters most, and I feel that's sufficient for what I spent. Other opinions may vary, and that's fine.