Good one, I agree completely.
I'd nominate Twisted metal III, which is right when 989 Studios took over. I've actually seen new publishers kill many series, as it happened to one of my favorites...
When EA took over Westwood Studios and Command and Conquer. It was never the same afterwards. I actually enjoyed a bit of C&C Generals made by EA, but I'd say the series lost me at Red Alert 3 or C&C 4, whichever one was first. Both were garbage and I'll never buy another.