Well that's the thing, that's why DC and partially marvel is trying to change that. A big issue was 30+ years of continuity to have to worry about. A lot of readers get confused when a current issue mentions something that happen in say superman in freakin 1986.
Ultimately, the comic book industry is dying. In the 1990's, comics would sell in the 400k range easily, with spawn topping the charts in the mil range.
Now, there biggest sales in a year comes from their "events", a mini series where usually the biggest stars from all across the company come together to stop some major threat. They are considered the most important issues put out each year, and this year, both Marvel's Event Fear Itself and DC's event Flashpoint didn't even break the 100k range.
If they did continue the way they did, and sales continue to drop, than it's a good chance that comics would stop being printed in the next 7-10 years.
With that said, there is nothing token or race swapping about miles, his first issue completely showed him to be a different character than peter parker.