Yeah, if you value your WDW visits, I'd strongly suggest not exploring. That's the type of stuff that got youtube user, Adamthewoo banned. Anyway, speaking of the man, he visited RC in 2010. Of course, he youtubed his experience and here it is
While I'm pretty sure no one is entirely sure as to why the park closed, the most logical reasoning (imo) would be that RC was fairly small compared to the other two. When it closed in '01 BB had already been opened for 6 years. Blizzard Beach is muuuuuuuuuuch larger, therefore, not only more rides, but bigger rides and more to do in general. While it seems like there was concern about parasites and such in the water, I don't believe it was ever proven.
I could be wrong on any of this, I do a lot of reading about this particular subject and everywhere I read tends to say something different.
I'm honestly more curious about Discovery Island. I read an article a while back on a group of people swimming there, but no matter where I look I can never find the article again only other articles alluding to that one.