If he let her go, there would be no show or game

The point of the story is them all dealing with their flaws and mistakes. Bella has good acting range, but she is not the same as the voice actress in the game. Lots of fans of the game don't like her. She comes across different in the show than the game too. She's actually more angry and jaded in the game.
They are making changes they say to make it easier to understand without the gameplay aspect, which there are some additional details you get while playing (that don't really change the story). Even though the main points hit the same, the show does feel different. The current episode is a good example - you literally don't see that porch scene until the end of the game. Bringing it into the main Ellie arc changes how it feels.
This season is OK, was hoping it would be better. You may like the flip side more, Abby's story sort of parallels Ellie's but she is very different. Will be interesting how she comes across in the show.