The reason I can get away with using just 10-15 different drum patterns, is that playing my own LH bass line makes the pattern unique. Think of it - in most real band situations, the actual drum beats are not THAT specific to each song. FIlls, and accents aside - the drummer needs to be more like Ringo than Steve Gadd.
I DO use the auto bass for some things ... I'd be foolish not to - it sounds so good, and frees me up to be more creative in other ways, but my staple sound .... my signature is LH Bass, RH Rhodes, sometimes with a string or choir pad, and a solid drummer. Everything else is fluff. I picture my act as a trio:
Drummer
Bass Player
Singing KB player
When I augment the routine with a sequence, or MP3, that's just more fluff. Sometimes, I need a lot of it, sometimes, not so much, but the core of the arrangement is always my RH playing most of the rhythmic chords stuff, even if I'm using an arranger pattern. I rarely play a single note melody with the RH. I like to "Paint" the chords into all the nooks and crannies of the rhythm. Playing my own bass lines allows me to "accent" or hit certain lines with a unity that can only come when LH and RH are free to work together.