You're really confusing at one point you say 5 years, and then 10 years, when it was actually 13 years later. I went to other events there prior to that and it was never really that well maintained. I was actually surprised the NBA allowed them to play there it was that bad. The only cool thing about it is the location, unless you're trying to find parking.
The ownership of the Sonics changed hands a couple times after the "rebuilding" of Key Arena. Unlike the Rose Garden though, doesn't the City of Seattle own the building? Unless I'm missing something that means that it's the city that let the arena go to shit, not Clay Bennett. It's further proven by the fact that they do in fact have to renovate it again now and are doing so.
Edit: The Rose Garden was completed in 1995 too just like the rebuild of Key Arena. I blame everyone involved equally if that place was crap a few years later while the Rose Garden is still in really good shape after 23 years.