Other plots that I have seen show new additions slowing long before TMI.
Each pre-TMI project was managed with a different level of skill, or with better rolls of the dice on timing, and those that completed quickly were profitable, and the those that had long delays had huge cost overruns due to massive capital outlays and interest payments without any revenue to back it.
And another reason that I don't think we can blame regulation: look at Vogtle and Summer. You have to dig really really really far into backwaters of blogs before you can even find somebody saying "this regulatory process caused us to be delayed," and even those complaints are vague.
It's not regulation, it's the industry.
We can look elsewhere in different regulatory environments too: UK, France, Poland, all have the same huge difficulties we do when constructing nuclear. The places that seem to have fewer difficulties still have difficulties. China has long delays, that would still cause investors to lose money in the US. South Korea had been on a tear of seemingly good construction, but it turns out that the contracting process was rife with corruption and now there are worries that unqualified parts are stuck deep in reactors that are supposed to run for 60 years.
If there is a regulatory delay on these projects, I'm not sure that there's any sort of appropriate regulatory structure that would make them work. And you can tell because the industry insiders that complain about regulation don't have any fixes in mind.