It's important to note that they (any content provider) has to do these operations real time, and you won't get the same gains from real time encoders as you will from off-line encoders. Where an offline encoder (think 5 or 8:1 vs realtime) has the luxury of multiple passes etc, real time encoders don't.
Over time, as Tom points out, the improvements will be more dramatic vs. MPEG-2 as the encoders improve.
Cheers,