Depends what you mean by "speeding up a BIT".There are a number of events that have been faster than the USO in recent years. It has not ruined tennis as you suggest. Not sure about this year, but Cincinatti courts are usually faster than the USO. Shanghai, Paris, London and a number of others are typically faster.
Grass, in the 90s, was the biggest problem. However, he has been slowed to the extent that several hard court events appear to be faster than Wimbledon.
A number of other changes have been made since those short rally days of the 90s. Tennis balls are brighter and have a little bit more felt then they did 25+ years ago. Possibly more important, string technology has changed quite a bit. Along with these changes, stroke mechanics and playing styles have you evolved.
So it is doubtful that speeding up the US Open courts a bit will return us to the game of the 90s that were largely determined by service winners or return winners.
I rarely watch indoor events when they're too quick, so...
When the average rally is 3 shots, I switch the channel to Gordon Ramsey or a Seinfeld re-run.
The 90s were putrid tennis-wise, we never should risk going back, not even a bit.