Why?
Why not, is the better question.
Disney has a huge library of characters that people enjoy. People come to Disney to see that. I don't see how the difference between a stuffy old man hosting a ride, or a character, really matter if the show is done properly.
People like characters, they think they are fun. That is why people go to Disney!
We can call them sheeple, or slow, or what have you, but characters have always been there. The 3 Callebros have been meeting and greeting at Mexico since the park opened. There seems to be this misconception that Epcot used to be devoid of characters - it's simply not true. Doesn't anyone else have pictures of themselves with Minnie in her space suit? The truth is, characters (the walk-around type) used to be much rarer in ALL the parks (even MK). The characters were there, even if they weren't hosting rides.
People keep holding onto this concept they believe Epcot was about, but forget that Epcot has always been, in it's final design, a theme park. We can talk about what Walt wanted to build, but we all know that battle was lost before ground was broke. ANd, to be honest, if they HAD built the city...uh, not so much fun. Practical, but not someplace one would take a vacation to visit.
I LOVE the older dark rides. Horizons, WoM, R.I.P. I love that type of experience, and I do miss it at Disney. But I think in the end, characters or no, it comes down to : is the attraction entertaining. Characters shouldn't be the "be all end all panacea", but they also aren't the bane of existence.
People seem to forget that WDW is not an altruistic experiment, but a vacation destination. You are never going to really "educate" people in a theme park ride; you can give them inspiration, but nothing more than a jumping off point. While a dose of education and to broaden your horizons is a good thing (to pardon the pun), the simple fact is at WDW people come get away from schools/jobs/etc. and while it's great to intertwine it, WDW was never meant to be an educational institution.
Just like people who want MGM to be a "real working studio!", sometimes you just have to let it go.
AEfx