I don't think the magic is gone. I just think as we get older we get far more jaded and it's easier to find fault in everything. Disney, first and foremost, is a corporation. It's there to make money. As adults, we know this going to any of the parks, buying any of the merch, trying to make reservations etc. You have to consciously suspend that belief to find the magic.
For awhile, I agreed with the OP. The magic was going away - but then I witnessed a magical moment while on the Friendship boat going from Epcot to HS. While on the boat (sitting on the back outside area) a little girl (couldn't have been more than four), was holding her Minnie stuffed animal. She went to scoot down the seat and her Minnie fell right over the edge into the water. Of course she immediately started to cry. Wail even. One of the boat CMs came back to make sure no one was hurt, and the girl's parents assured him she was fine she had dropped her Minnie overboard. They apologized for her crying and tried to calm her down. The CM went back up to the front of the boat, and carried out magic. By the time the boat docked at HS - there was a CM standing there waiting with the exact same Minnie stuffed animal. The family got off the boat right in front of me, and the CM proceeded to tell the little girl "Minnie got overly excited about coming to Hollywood Studios. She swam all the way here! She missed you though," and then gave the little girl the Minnie.
So the next time we think that the magic is vanishing? Keep your eye out for something like this. The magic is still there. You just have to be open to finding it.