So watching people explode with anger all over the Internet has been quite entertaining. The TV series was not affected when the Peter Cushing movies were made in the 1960s and I don't see this as being any different: an interesting side-spectacle unrelated to the core series itself.

It is, however, disappointing that they didn't think in a bit more of an interesting manner: a hitherto unrevealed between-incarnations version of the Doctor who fought in the Time War (not alluded to onscreen but not ruled out either, with between-regeneration versions of the Doctor established in the earlier series) could have been an interesting direction to take, but the more logical route would have been to have had a younger version of the First Doctor stealing the TARDIS and fleeing Gallifrey. The Doctor is, by far, the highest-profile fictional character in current popular media never to have had an origin story established. They could have done that in a manner that didn't contradict existing continuity and fans could have been free to take it as a non-canon side-story or a proper prequel to the TV series.