I agree about some of the later scores for the color seasons, but the early episodes score by John Williams, etc. were fantastic. Iconic music and some of the best TV scoring, like, ever.
Agreed. The first seven episodes of LOST IN SPACE had stunning scores that left an indelible mark and nudged me toward of lifetime interest in film music. Even the worst later episodes can hold my attention when they're tracked with the early music.
On the other hand, later episodes with original scores had music not so good. Just compare Gerald Fried's STAR TREK scores to what he did for LOST IN SPACE. His LIS material contains extremely faint echoes of the ST music, weaved into a lot of meandering and mush. The later LIS stories just did not inspire composers to greatness.