I would think it's a good idea to get there when it opens, if only to be part of the "stroller brigade" waiting for the gates to open (yes there are gates to TT).
We had a very nice character experience during a rainy MTTMM, but we also had a different, but still nice, character experience on our last trip when we didn't have MTTMM vouchers.
The first, there were Mickey & co characters all throughout Mickey's house (which is just a big, long, cute queue), and meeting them in the entryway, living room, hallways, and such were a good way to slow everyone down.
But this last trip, there was no one but Mickey, BUT Mickey was in a room with something like a backdrop, and 4 families or so were admitted at a time, so each family could have a nice picture-time with him. And there was a photopass guy with Mickey this time, which made it so much easier on me.
None of this is to say you can't see Mickey etc throughout the park at various times during the day. On our very first EE day in September, we were slowed down by the sudden appearance of Mickey and one or two of his other friends just after the AP center. Minnie was at the Paradise Pier breakfast. Goofy and Pluto, especially Pluto, has been spotted by our family many times, and DS wants to meet them each time, LOL.
Anyway, although the outside of the lines at Mickey's house is long and rather boring, once you're inside it's kind of neat walking slowly and looking around, and when you're actually interacting with the characters you can see why it's long, because it can be more than just a smile-picture-go sort of thing.
Really quick, after re-reading your question. When you write MM you mean morning madness, right? They've decided to mess us all up by calling the early entry thing Magic Morning, which of course is MM...when they already have MTTMM, and it's all very silly of them. But I think you meant "is it worth going there if we didn't have MTTMM", right? Yes, it is.
And if you go there early on a day when there was no MTTMM, then it's just like going to the gates on a non-early-entering day, b/c everyone is on the same footing!
