You're right. It could work, and Marvel may have a really good story brewing. But for every attempt at something like this that succeeds, there are multiple that fail, and while failure may not have a massive direct impact, it would definitely hamper the creation of further new characters along that line, which doesn't need any more obstacles than it already has. In end, regardless of the name recognition or the story, this has be treated as trying to create a new character as far as setting odds and expectations. And the odds of a long term success, are frankly, not all that good, which reduces this to a temporary gimmick that will piss off as many people as it will please. If it was an alternate universe, like they did when they replaced Peter Parker, where Peter Parker was still around in the main universe, it wouldn't be that big of a deal, but for the mainstream story, this is, quite frankly, a bit too much a bit too quickly for them to really fully control the end result, and that could be problematic.