I've read that the cast HATED those stupid episodes. That they felt it is what wrecked the series. It was just so mind numbingly ridiculous that it severely damaged the brand. That's also what I thought at the time.
The fact is, the cast in Lost in Space was solid. Viewers cared about the characters. Kids watching certain episodes got more creeped out by "Mr. Nobody" and those lumps of dough turning into zombie Dr. Smiths than yet another threat to vaporize the planet.
I watched that show as a little kid, and I knew after the first episode that they needed to put into action Major West's plan to "Put Smith into the Air Lock".
Time and time again, Smith jeopardized everyone's lives, and they shouldn't have given him a second chance.
Of course without the "Smith" factor, the show would have never had a crises, and therefore would not have been watched, so what does a little Kid know about television anyways?
It might have been interesting to make Dr. Smith the sinister character he was in the first two episodes, instead of the coward he developed into. Maybe they could have made the Robinsons Quakers or something. The show also could have used more Judy.