the DEMO is fine, i played the demo (ok it was S1) for 6 months before i could buy a licence, it was fine, i didn't get bored, I just concentrated on being as fast an as clean a racer as i could be. if you're the kind of person who'll get bored with what you get (12 combos in all) then you're probably not the kind of person I wanna be racing.
LFS takes a fair bit of practice to get up to a competent level, i say leave the content alone as i gives the noobs something to concentrate on.
and if you've been playing the demo for more than a year, then bollocks to you whinging about more content, there can't be many people that can't afford £2 a month (in the west at least)