Eh... I'm not really a fan of having every game be isometric. I really think the more cinematic, action-oriented games, like Grand Theft Auto or Uncharted, benefits from closer, direct perspective. I do agree that there needs to be a greater number of isometric games, if only for more variety. I think we're all just having this opinion because we're still reeling from the technical nightmare that Fallout 4 is.
If there's a good argument promoting more isometric turn-based games, it's that it's even more accessible to more people, if general audiences can get over having to put action in every game. The accessibility is due to the fact that there's no arbitrary need for intense use of eyesight or reflexes. This feeds to a "at your own pace" kind of experience, which a lot more people would appreciate if they took the time to attempt games like these.
I know so many people who would appreciate a good game and a good story, but can't play modern action games due to shaky first-person cam and speed-shooting sequences disorienting them. I really wish the modern game industry had a more balanced market. Something for everyone.