As others have said, 30 minutes is nothing. If it was an hour, I would be a little more accepting. We've all pointed out, 30 minutes gets you maybe one ride. If that early entry was what helped determine if I stayed on Disney property or not, I would choose off-site every time.
MDE was always a great thing, it definitely encouraged me to stay onsite and fly into MCO. Now, I would definitely reconsider. MDE truly was a deciding factor in where I stayed and how I approached my trip to Disney World.