There were supposed to be advantages to building four at once, in that there would be some economy of scale. The AP1000 were also supppsed to be somewhat "modular" to avoid on site custom builds. None of this worked out as planned.
If we wanted nuclear to be a part of the energy transition, we didn't need two new reactors every decade or even four, we needed something like 5-20 per year. However, the experience of building the AP1000 has soured the market.
If we are going to build more nuclear, now is the time because we have the most knowledable workforce right now, but the benefit of building nuclear looks so small in comparison to the cost and the risks that it seems unlikely.
Major major support from the government is needed (and it's there from DoE's Loan Programs Office, run by a huge nuclear fan), but you also need utilities who want to place orders. And that second part is hard to create.
Westinghouse used a new regulatory process that had been created specifically at the request of industry to speed the design and build of AP1000s. Despite this, Westinghouse did not deliver constructible designs, and the contractor soldiered on with on site modifications. Westinghouse screwed up so bad that they nearly bankrupted Toshiba, their owner.
So we have two failed holes in the ground at Summer in South Carolina, something like a $10B monument to corruption, with utility execs going to jail for their fraudulent reports.
All the other sites that were eyeing AP1000s to replace aging reactors have now backed out. The disaster was too big. What exec wants to go to jail for a nuclear reactor? What exec wants to lose their job for greenlighting what has a not-insignificant chance of bankrupting the entire utility.
Nuclear is too risky, but public perception is off, it's not running reactors that have the risk, it's the financial risk to anybody who wants to build one.