I have heard that it would be cost prohibitive for Disney to re open the park. There were several issues at hand. I can't remember exactly where I read this but this is what I recall:
~The new standard for bacteria vs. the lake water....they would have to re-do the whole filtration system.
~The slides were no longer up to code and some of them were in need of major repair, cement, wooden structure, the whole 9 yards.
~9/11 impact on fewer tourists were also a small consideration
~they felt the 2 newer water parks fitted the needs of all guests
Hope this helps!
I too was a River Country kid....I would love to someday share that park with my kids.