My 2006 E90 had black leatherette, and I never had any issues with it. One spot on the driver's seat was starting to crack, probably a combination of getting in and out, and how I sat. It never hardened, or otherwise got distressed.
I just sold it and bought a 2009 with beige leather, so now I feel obliged to treat it better. It's still in good shape, so I'm expecting minimal wear from it.
In general, I'd say it doesn't matter as much. It's easier to be more forgiving with leatherette, so if you have kids or lots of passengers, it may be better for your sanity.