They've already done what you ask, both in the form of Ultimate Spider-Man and the re-boot, with varying success.
But a restart isn't the answer. Quality writing, artwork and editing is.
I've said it before as well- I've never been fully onboard with the Spider-Marriage. During Conway's run, there was a nice build-up to Peter and MJ getting together, and I was totally in favor of it. Obviously TPTB weren't, since during Len Wein's run, Peter and MJ essentially went back to just being friends. I was recently re-reading the Hamilton/Goblin arc (Which was better than I remembered). And each time Peter ran into MJ, it was like back when Peter was with Gwen- they acted like old buddies, not like two people in love or even infatuation. Then there was Peter's proposal, that was completely out of left-field, and only because he felt lonely and envious of the relationships Harry and Flash were having. MJ turns him down and that appeared to be the final nail in the coffin, with Marv Wolfman filling the grave with soil by making it doubtful they could reconcile.
So 4 years later they bring her back, make it clear she's not interested in Peter romantically and Peter "moves on" (If it could be considered such) to Black Cat. Then after that even worse relationship choice ends- they have Peter again out of left field, propose to MJ. No further development as to why these two should be together. It didn't help their case in my book that this period had some of the absolutely worst writing in Spider-Man's long history. Then of course they toss in the supermodel thing. On the Peter-MJ appreciation thread there are tons of postings of pages between them. And for me, those postings underline just how poorly this marriage has been handled. They speak to each other in platitudes. They don't simply talk. Someone compared MJ's speech to Peter about why it was time they made love after their separation to the work of Stan Lee. And that's totally wrong, and pinpoints the problem. People can look at Stan's work as dated. Maybe it is, as he was writing to a specific time. But the difference is- that Stan wrote people communicating with each other. Relating to each other. that's why the relationships always rang true. Guys like JMS, write people talking AT each other. Doing dramatic monologues meant to present the idea
of who they are and the power of their situation across. It's artificial. I mean MJ's speech was the most unsexy way of saying she wanted to have sex.
The marriage happened during the worst years of Spider-Man, and for me is a symbol of that.
So, no. I wouldn't stop buying Spider-Man if MJ was killed off. However- I would stop buying the comics just because MJ is being killed for the same reasons that the writing has been consistently bad. So her death certainly won't signify any kind of new and glorious era for Spidey. Just the same damn crap.