This is in response to security concerns for some EU countries, so it's really just a political tit for tat. "The United States has been in a dispute with the EU's European Parliament and European Commission over visas for Bulgaria, Croatia, Poland, Romania and Cyprus. Travelers in those five countries are the only EU nations that the US requires to apply for a visa."
The EU is acting as a single political body, that's good. The US requires a visa for visiting from the EU, thus the EU requires the same to USA visitors.
There is no obligation for countries to always get bigger, or for countries to pretend there's no regional variations. ESTA is a pain and stupid and it gives me a worse impression of the USA every time I have to fill it out. There is no reason why the rest of the world should follow suit.
I see nobody else has said it yet, so I will - I hope that after Brexit the UK can drop this ETIAS nonsense and be more welcoming to Americans, even if they don't drop ESTA in response.