Improvisation was an important part of King Crimson, especially in the early days, and my guess is that Fripp wanted to capture some of that on record. The biggest problem, as I see it, is that it really should be relegated to live albums and not take up space on studio albums. If you buy a live Crimson album, you expect at least some improv tracks. Studio albums, I'm looking for more structure, tunes that are actually composed, with maybe a section or two that are improvised.
Even Red, my favorite studio Crimson album, has "Providence" which I often skip. Actually, for a long I assumed it was a studio improv, as he fades it out before the end. It wasn't until much, much later that we learned that it's an excerpt from a live recording. In which case, I'm not sure what the point was, except to include it on an album just because he wanted it out there.