Starless was the perfect conclusion to that era of the band. It's essentially the climax of the band's 70s career, and wraps everything up perfectly.
Semi-tangent: It's still surprising to me that they kept the name from Discipline onwards. It's clearly not the same style of music, it only shares two of four band members, it was released seven damn years after Red, and from my understanding they never played much of their old stuff live during that era. It's still a fantastic album, but it's not King Crimson goddamnit.
Well, I guess it's up to you if you beleive him or not but to give Fripp credit, since about mid-1973 or so, he's been stunningly consistent in his assessment of King Crimson. It's not about him, personally (though he's been on all the recorded output to date, only man to make that claim) but rather a "way of doing things". He makes music in and out of Crimson, with artists who have been in and out of Crimson, but when they get together, it seems to take on a life of it's own.
I know this might sound condescending, but I don't (at all) mean it that way, but this only becomes clear when seeing them live. It's very much a performance, not a concert (which is why, I believe, they DON'T play a lot of older material). Very heavily improv driven, and very much in the moment.
Interesting story: I saw them in November '95 in New Haven (Palace Theater). At the time the big buzz was that the Beatles were going to release a new song - Paul! George! Ringo! John on tape! - and Adrian Belew (noted for his sense of humor) came out for his solo set and proclaimed that he had the song and was going to play it for us. And he did this beautiful, voice and guitar version of a song that had the lyrics "Free... free as a bird" and we laughed and clapped. Two weeks later, in December, the big reveal, and son of a bitch if it wasn't the exact song. (I actually have a tape of that show; I met Sean Lennon not long ago at the Palace before their show - they cover King Crimson in their set - and I got scared and didn't mention that. I should have.)