It got away with it cause it was a change people wanted and had the possibility of bringing life back to the dying franchise... thats kinda how things roll nowadays unfortunately. The plus being that the reboot respected the original source material.
Personally I though the XCOM shooter thing was stupid, straying away from the core mechanics for a wider audience is sort of a wuss move.
Not all games get away with it. Just look at the wild ride that was the new DmC:
-Franchise was dying, needed some sort of sequel, instead got a reboot.
-Now this is where things fall apart... trailer for new game revealed, majority of the fans DESPISE the new character design, new studio/director working on the game insults said fans, pro-DmC fans call us whiners backing the new dev team and the game.
-Dev team is eventually pressured by old fanbase, attempts to appeal to them are made (uncreative white hair devil trigger, Donte no longer smokes), it fails, devs and pro fans go back to insulting us.
-Gameplay trailer is revealed, gameplay is seen to be slower and simplified to the point where its nothing compared to original DMC standards, attempt to win back old fans fails again, devs and pro fans assume we're still mad about the hair and not the dumbed down, piss poor demos shown.
-Demo comes out, old fans still don't like it, Donte remains unlikeable in design and personality, pro fans tell old fans to wait for the full product to apparently have the right to an opinion, we wait.
-Game is released, poor sales, glitchy glitchy glitchy, poor story, poor characters, decent but slow combat, suspicious number of high scores along with comments of it being superior to the original games, evidence of multiple flaws are shown in unbiased reviews, pro fans assume we're STILL mad about the hair.
-Devs try to appeal to the old fans AGAIN, release old Dante skin, fails AGAIN. Fans are now forever alienated.
So yeah not all games get away with it.