Marvel is happy with 616 Spidey again because he's single again, the marriage never happened and they can pretend he's still 23 or 24, tops for the rest of his existence (even though he seemed close to 30 until that abysmal story). Personally, I despise OMD so much I have hardly looked at it since. But to Marvel they have "succeeded" at deaging Peter and don't feel they need the young high school Peter in Ultimate anymore, because Quesada was convinced ten years ago that is the only true form of the character.
Personally, I hope Peter stays dead. The 616 run ends either by pretending it merged into Spider-Girl (the DeFalco series that ran for like 15 years or something that i have some of the TPB of), Reign if you're a misanthrope, or just anything but what it is now. I like USM just fine, but I never was endeared to him in the same way and after seeing Marvel massacre what made the character special in their main universe, seeing him actually have an ending and finality with real character integrity in USM really makes me give props to Bendis's vision of the character's story (granted I only read in TPB the first 50 issues or so of USM before the "Death of" ending).
Miles Morales is interesting from what little I've gleaned and I like they're giving the world a new Spidey that can appeal to a more diverse audience in the 21st century. I also like how it seems everyone who dies in the Ultimate universe (Spidey, Wolverine, Daredevil, Cyclops, Xavier, Doom, Magneto, etc.) stays dead. The only exception I know of, ironically, is Gwen Stacy. Who despite Joey Q's horrible ideas has thus far remained thankfully deceased in the regular series.
All this is a long-winded way of saying I like what they did with USM. Granted, I'm not a diehard of the series or have read all of it. So, I think it should stay the way that it is in the current form.