QT 6 was good, why is 7 not?

I have an older Mac, a G4 450 agp.  I currently do not have a cash 
needed to even upgrade my cpu or buy a used MDD on eBay.  That having 
been laid out, my question:

QT 6 allowed me to run the "large" sized movies that played at 480 lines 
by 640 or wider at full frame rate and all was well.  Now, under QT 7, 
the smallest size MooVs are 480, and they play worse than WMV files tend 
to.  Why did Apple have to revise QT so high from 6 to 7 that the lowest 
quality videos play worse than QT 6 highest qualities used to?

jt