Maybe not in a herc PAF (why LMAS didn't include it in the J still puzzles me - ah that's right - we're cheap!), but it can make life very difficult in a passenger jet. The difference, for example, between doing per-syd at >FL300 and being stuck down <FL300 can be very substantial in fuel, time, etc. Multiply that by hundreds of sectors per year, and all of a sudden your business acumen isn't looking so good after all.
...and the frequency with which the most fuel efficient planned levels happen to be non-rvsm? Well, so far in my experience, zero!