If you have realistic expectations, you'll be fine. We make a few ADRs and/or book a few activities, get an idea of hours, etc. before we go and have a general idea of what parks to hit (or avoid) each day. We tend to work around the more important ADRs and activities, but tend to go with the flow when we are there. The key is to have the knowledge to say to ourselves, "we don't want to do such and such today, but we know we can see it this other day". When a plan is too detailed, it's difficult to take in the whole picture and let go of the plan, when necessary.
I dislike the dining plan because it has resulted in the restaurants being more booked with ADRs than before the plan was offered. I dislike trying to figure out 6 months before my vacation where I'm going to be and at what time. So many factors come into play, the crowds, my mood, the weather, my kids' temperament, my husband's temperament. I force myself to sit down and lay out a framework knowing I'll probably end up changing it close to or during my trip.
So, no, you are not crazy. If anything, you are trying it at a good time.
Have a great vacation!