And what else should he do? He's limited to three octaves, and so he uses only three octaves as best he can. I'm quite certain if there had been five available, he would have happily made use of them for a much fuller sound. With only three octaves, the bass will obviously have to come from some other source.
If a synthesizer is only a sound source, then let it be a module. If it's a musical instrument, then fully equip it for music-making with a generous keyboard. I mean, at least Roland gave the original instrument four octaves. That was generally the keyboard length of string synthesizers.
This dumbing-down of instruments drives me crazy, as if the music itself was only an afterthought. More parameters, more functions, more effects, more computers...and fewer keys. It's materialism killing art.