Marvel can relaunch every title every 12 months as far as I care, but relaunching titles with a new #1 is something Marvel has been doing ever since I can remember (going back to the '70s). They'd simply stick into the indicia at that it's Vol. 2 or Vol. 3 and people just went on with business as usual.
Back then, it was for titles that had been cancelled/ceased publication and then had been brought back after while. These days, there's definitely a business element behind doing so for some titles to attract new/more readers who look at an issue #1 as a jumping-on point. But they do seem generally to tie such relaunches with something ending or beginning story-wise (either in that particular book or in the larger universe it's set in).