Neal is a great musician, and a prolific composer, but he's also a keen businessman. He knows his bread and butter is making symphonic prog rock, particularly with Portnoy on drums. I'd argue that getting MP to play on his solo albums after he left Spock's, has helped his bottom line over the last 20 years, due to MP's popularity from being in Dream Theater.
Even then, I don't think he's a very popular artist in the grand scheme of prog rock, let alone all of music. So many prog fans do NOT like Neal's brand of prog (or TFK, or many other 3rd wave prog acts) If he couldn't make it as a singer-songwriter in the 80s and early 90s, he sure ain't going to break out big as a 61 year old white Christian male musician living in Tennessee in 2021, what with how our media pushes negative views on older people, people who live in the south, and religious folk, particularly and mainly Christians; and what is considered 'mainstream' music these days, which sometimes sounds like anti-music (and not in a good way). You'll be lucky to find someone under 40 or 35 who's even heard of Jon Anderson, Robert Fripp, or Keith Emerson, let alone Neal Morse. You might get lucky with a Collins or Gabriel, if only because they had a few pretty big hits in the 80s that still get airplay to this day. Even then...
Neal plays a niche style of music to an even greater niche audience, and yet, he's one of, if not THE most popular prog musicians post-1970s, aside from all the Dream Theater members and ex-members. It's basically a sad state of affairs for the genre, to think, ELP were playing huge arenas in the 1970s...