well he uses different equipment on different tracks. the madvillan cd i think was made with just the sp303.
yea it is totally true that a good producer/musician can make good music with minimal equipment, and thats something that madlib proves on those tracks where he uses just the sp303, but i think it proves something else too....
when a producer has the luxury of picking his equipment without many cash restraints, it is sometimes good to go for workflow over functionality. samplers especially sound just fine in general, so yes while a good producer doesnt have to jump for the crazy functionality of a sampler on steroids, it is good to pick according to your personal workflow. i had an sp303 for a bit and i loved it. i had been using reason/recycle/acid to work with my samples, and they had a TON of functionality when used in combination, but as soon as i got the sp303 my beats got a whole new flavor and i loved it. i just approached the tracks differently with a different workflow.
modern mpc samplers dont pack much more functionality than software samplers (arguably they provide less functionality than certain software samplers), but they cost waaaaay more and still sell like crazy. so what is so special about the mpc series? well, aside from the cool sound coloring (that little punch it adds to samples), mpcs have an unrivaled workflow for drum/punch-in sequencing. yes, you can program the same stuff by clicking in midi tracks to your software sequencer, but the mpc workflow just FEELS so much cooler, and you might come up with better stuff on an mpc. like pete rock said, you feel really in touch with the music when you work on samplers like that, which might enable you to make better music.