see those tubes up there at the top of that unit? They definitely add warmth and drive to whatever samples you run through that machine, depending of course on the tube gain that you apply. You're not gonna get a well rounded tone like that out of ableton without additional equipment.
And when you think about it, to say that taking a signal and running it through different hardware/software samplers/sequencers is not going to change the tonality of the sound, its like saying that you could play a G chord on a Strat and on a PRS and they are going to sound exactly the same (when played through the same amp). Different hardware produces different tonal characteristics, thats why some people swear by Akai, some by Roland, Korg, etc (hardware options) and others Ableton Live (really the most commercially viable software sequencing application for live use).
Also, how is an MPC (or any other sequencer with tactile input for that matter) any less of an instrument than a synthesizer?
That's like saying "I hate when my beer is cold" or "I hate when titties are nice feeling". Get outta town.