My question on this is why make a sequel with an unrelated game? Games can use the same IP and setting without being sequels... Other companies do this all the time; there must be a dozen Warhammer/WH40,000 games, but only a couple sequels among them.
TES at least ~does change the name... There are 5 games that use the Elderscrolls setting [that I have heard of]. And it's fine that they are different each time; they did not make Morrowind 2, or Oblivion 2, or Skyrim 2... Had they released Oblivion or Skyrim with the name Morrowind 2 ~~That would have been disingenuous IMO, because the games are almost completely unrelated except for the setting. Oblivion and Skyrim improve on nothing from Morrowind, they are their own games.... Although it's arguable that Skyrim is close enough to almost pass for an Oblivion 2.