WDW is for entire families, not just kids. They have attractions (contrary to what Walt desired) that ONLY accommodate children, and others that ONLY accommodate "adults" (height requirements, thrills, etc) - but it would be boring to have theme parks filled with only rides that literally everyone can enjoy together. It would be 100% dark rides and boat rides.
Regardless, I don't consider WDW to be a destination for children. It's an ideal family destination, which offers something for nearly everyone. Children, families, extended families, couples, young adults, seniors....they can all enjoy something on property, even if that "something" is sitting on benches, enjoying ice cream and crowd watching.
I'm 35, and I've been going since I was 6. My wife has only been going since I first took her on our honeymoon in 2008. We're both adults, and we love WDW.
Our son is now 7 months old, and he'll get to experience it on his first birthday in November, then again in January. We hope he loves it as much as we do, and we're excited to re-live the experience through the eyes of a child.
To address one of your major points, yes, I believe there are many people in the world, and on these forums, who think Disney needs to be Six Flags and cater only to thrill junkies. And they (in my opinion) become unjustifiably disgruntled when Disney invests in attractions like 7DMT.
I honestly don't care if someone doesn't like it because it's a "kiddie coaster". It's PERFECT. Entire families can ride it, and everyone can enjoy it. It's a great way to introduce kids to coasters, since it's pretty tame, but is actually entertaining (unlike Barnstormer).
The people who can't handle Disney putting in family attractions should probably migrate to discussion boards for other types of theme parks.