Probably because this project has been in development for decades and overran it’s timelines and budgets multiple times (to my knowledge). Congress already hates funding NASA, can’t imagine they were lining up to give them more money when I’m sure they had been asking when’s this thing even gonna come out?

Also, FWIW, this thing has 100+ points of failure along its route to being fully deployed and getting to the L2 spot. A lot of people thought for sure at least one area would malfunction, would have easily doomed the whole launch. After this successful launch, it’s possible we’ll see discussion on building another in this design, but there is already a telescope in the planning stages for a 2027 launch, as well as four other concepts being developed for the future.

https://en.m.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Tele...

https://space.stackexchange.com/questions/57407/are-they-alr...