As a maintainer of a devtool which has strived to make itself easily forkable and modifiable, I can see the allure of this line of thinking but I think it's sadly too idealistic.

Engineers using devtools are not so different to an average user in that they just want things to work. Maintaining a devtool is real work; e.g. suppose upstream adds some feature you want but it clashes with something you did downstream. Not in the merge conflict sense but in the UX sense. Do you want to resolve that on every release? Is it just "AI will fix this"? Maybe one day, but as of today agents can do something along the right lines but don't capture my UX sense very well; and if the whole point is hyper-personalization, I want it exactly how I want it.

"Does it seem to work?" is a fine right until it fails when you're doing something important. Do you then stop and go prompt an agent to fix your tooling, and hope it does a good job this time? What if it doesn't do a good job?

Moreover, for devtools which are fundamentally social (i.e. lots of different people looking at the same thing), there's real value in that thing looking the same for everyone. Having a baseline for teaching, auditing, verifying "we are all talking about the same thing" is incredibly valuable and is sometimes where the most value is.

All in all, maybe in some categories of devtools, this hyper personalization is indeed what will happen but it's a long way from being universal.