With anything potentially being re-developed, it's always sad, but usually it's for the best. I miss Jaws and Merlin Woods, but their replacements are superior. As long as anything replacing an existing land or attraction is in some way better, it's an understandable sacrifice if they re-develop.
Personally I love Toon Lagoon. I think it's clever and well done, but if there's a better thing to replace it, I'll survive.