It started off as an update. More stuff was added. It became the Enhanced Edition. Somehow that means Larian doesn't care about those who bought the game.
It can not be a cash-in if it is free to everyone who owns D:OS.
The history of computers (obsolescence, reliability, etc) suggests that virtually everyone will upgrade eventually. I used (and am still using) my old computer for more than a dozen years past the the last upgrade it made sense to make; much of that time I didn't have the money to build a new computer, sometimes I did but couldn't justify it when there other things I needed to deal with first, but eventually (a year ago) I had both the money and justification.
Other than the switch from DX 9 to 11, and becoming 64 bit only, there is not going to be huge jump in requirements.
