That's the sort of corporate strategy that, really, actually pays off. In the same way that Marvel giving more books to female and minority characters not because it's the right thing to do, but because it means they sell more books to a wider audience and make more money. It's not the right reason to do something, necessarily, but it does end up with a net positive result, so what's the harm? The retconning is mainly so they can cancel the Ultimate line without losing the Miles Morales audience, and so they can appeal to the people who watch the films, but that's probably a good thing. Marvel have been commended for never abandoning their continuity to the same extent as DC, but maybe that's not something that should be commended. Even now, it's difficult for somebody who has never read a comic before and who has most likely been turned onto them by those mega-popular movies to make a start with them. There are unspoken histories, relationships, which they're totally unaware of. People are wearing different costumes. Nick Fury isn't Samuel L Jackson. Ultimately, Secret Wars isn't going to render the Marvel Universe completely unrecognisable to long-term fans. But it might just bring in some new ones, and possibly even tell a good story along the way.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/