For the most part, modern games do a pretty good job on surround audio positioning. There are the outliers in some of the Halos or Call Of Dutys that completely ignore the center channel, feeding the receiver dead air, but those really are in the minority. A more disorienting problem is in 3rd person perspective games that put the audio render home position at the character's location instead of the camera's position.
As for whether the center channel is needed for humans to appreciate surround audio? City, you are giving the human audio subsystem far too much credit. We are bad at hearing. It's not nearly as bad as our terrible visual subsystem, but it is still quite poor. We have two ears, not three, not seven, not forty. Given our two ears, pick any number of speakers, an appropriate software solution for them, and a properly designed source and you rapidly get to the point of "good enough". Two speakers fed an appropriately mixed source with phase tricks involved is very good at fooling our fairly simple human audio subsystem. Why? Because humans are far better at being clever than they are at sensing things. Well, one human isn't, but generations of humans have been building on this science for ages. Standing on the shoulders of giants, yo.
So, is four channels a problem? Absolutely not, if it's mixed properly.
To make a suggestion: How about instead of paying attention to the numbers and worrying about whether your center channel is getting the work that it should, enjoy the game being presented. A crap game in 8 discrete channels with poor audio engineering is not better than a stereo game with great audio engineering and great gameplay mechanics.