Well, whether or not I agree about all the new transactions available in OW2 is good or not, I'm not gonna argue on. But, OW1 was released 6 years ago. Some games shut down their servers after 6 years. You purchased OW1 for the coming years until OW2, you didn't pay for it to last forever. And how long the support would be, noone knew, but if you buy a game and hope that you always for all eternity should get support for it(or in this case, not having access to heroes at the start anymore, than that's kinda on you.)

The people payed for OW1, not for OW2. OW1 and it's core system will kinda cease to exist, which pretty much happens for any game at one point.

If they instead just said OW1 would shutdown, and no sequel or anything, the game would just be removed. People would obviously be mad, but it's not their right to be, because they paid to have access for the moment, but not for the rest of their life.