When they've done an xp bonus over 4th of July for many, many years, and people plan on it, yeah delaying it because of a problem on what amounts to 4% of their total servers would be a big deal to everyone playing on the other 96%. Live players already enough about TLP's screwing their game up (with often good reason.)
I was playing those times you listed. I didn't have a single issue whatsoever. in fact, this entire week of bonuses I've had a fantastic time and leveled a Shaman from 4 to 40.
I was so sad when it ended, definitely wanted it to go on longer! I also hate that they start it at 12am PDT but end it at 11pm PDT. Like, why? Just let it go until 12am ;p