Or, it's just poor audio mixing in the games. Also, a lot of times with movie DVDs/BDs, you can select the audio track, so make sure you're not selecting some surround sound format. The PS3 is perfectly capable of using such formats, it's just a matter of whether or not your TVs are without the help of a receiver or something to decode the signal.
Also, linear PCM isn't really going to help either. That just sends an uncompressed audio signal directly to each speaker, but you can do surround sound with that just as easily as any other format. You want to find something specifically marked stereo or 2ch/2 channel. I haven't tinkered with the audio settings on my PS3 in ages, so can't say where exactly to look, but you sound capable enough to be able to manage this on your own.