I liked seeing Max and Millia (and Exsedol) in 7 and Focker in Zero, but I do agree that the rarer that kind of thing is, the better. I certainly don't want to see the Macross Frontier fleet come across the Megaroad-01 but get attacked by the Marduk, only to be rescued by a search team headed by Gamlin and Ismau...not that I think that will happen.
I think one of the important things to recognize about MF is that it's on television, and as such, can't be narrowly aimed at only the Macross fanatics, but has to draw in a new crowd as well. Sure, they can throw us some fan service in the form of Sheryl shouting "Atashi no uta o kike!" or Alto's VF-25 being the spittin' image of Hikaru's VF-1D, but they certainly can't expect the audience to have a every moment in Macross history memorized.
Look at U.C. Gundam...Zeta and Double Zeta had some recurring characters from other series, but the focus was always on a new batch. (Even then, the amount of Gundamology one had to know to watch any new series was so daunting that they came up with the AU stuff to start over from scratch.) Max and Millia remain mostly in the background in 7, while Fire Bomber struts its stuff. We may come across more "echoes" of previous events, and a couple of familiar names and looks may turn up (not to mention voice actors and actresses), but recurring characters from previous series? I don't see it happening...unless the ending of Zero was left open specifically to tie it up here, but I kind of doubt that.
All that said, we've only seen the first episode, so I suppose anything can happen between now and whenever it ends. But I'd be willing to place a (small) bet that it won't.