Agree with a lot of what's been said. Back in the day, it was often said that on SWT, 442 1st was the best, followed by 442 standard, which was on a par with 444 1st (except that had reclining seats), then 444 standard, which was on a par with 450 1st (I disagreed), then 450 standard.
These days with the 442s gone and the 444 1st "refurbished", I'd say excepting the 158/159s, the 444 standard seat is the most comfortable seat on SWR's network. Followed by 450 1st, with 450 standard and 444 1st on a par with each other.
Returning the question of "what is the point", I think the point is purely to provide a seat on services where there might not be one in standard. It certainly isn't going to be anything to do with comfort or added services. I've stopped upgrading on weekends; standard class is plenty good enough.
If passenger loadings were as they were pre-covid and had continued to increase then I could see 1st on the 450s being withdrawn in favour of more standard. Hopefully the 444 standard doesn't get refitted and downgraded as they've done with 1st.