I can't prove it, but i believe every building at WDW is 3-4 degrees warmer than it used to be. SSE is definitely one of the worst offenders, but definitely not the only one. Also, if the A/C didn't work at all, you would probably not be able to ride it without passing out.
It's a clear way to save money across WDW.
That said, I'm mostly comfortable in every building and I still say Disney has legendary AC overall. Honestly, the "warmer" restaurants are welcome at times because while that AC feels good the moment you walk in from the heat, you can be pretty chilly during you're meal, which isn't always desirable.