If it wasn't for Smith, they wouldn't have a show. This is an old series, but at the time, it was a great show when I was little and watching it. It brings back a lot of memories. I remember when I was little we use to get mad at the way it ended. But it ensured we would tune in the following week.

They could have used the pod to recover Doctor Smith; that way, they would've saved their rocket fuel...

C o r n y e p i s o d e lol

The only reason why Dr Smith was not rid of a long time ago in the episodes due to all his sabotage and mischief, (aside from Irwin Allen the producer of the program to decide and keep him) was to portray the genuine compassion the Robinsons have in general for human forgiveness regardless of the violation. And when one thinks about it, whenever there is any moral standards or laws broken there is at least a place for everyone of those violators--on Earth, (ie, penalties, fines, incarceration, etc) but at least they can survive and redeem themselves there. Given that the entire family is remotely millions of miles away from civilization, leaves only to consider that the Robinsons, may have realized resorting Smith only to an all or nothing recourse for his evil deeds, that is to either abandon him in space or tolerate and keep him under scrutiny in order to prevent any more of him putting the Robinsons in jeopardy. It’s hard to comprehend that the Robinsons are always tolerant with him and forgive him, on every scene that follows a mishap of his. To abandon a human being in space with nothing to live on in uncharted areas, would be probably worse than the ultimate capital punishment, since being in space alone would be slow death and solitude without resources of survival. If this drama has transpired all on Earth, Smith would have long since been gone and out of everyone’s hair.

Smith has tried to kill them, stolen their thrust control, and caused general havoc. Yet nobody keeps him away from the nav controls. After he nearly destroys the ship, they still pay no attention as he returns to the nav controls.Being forgiving doesn't mean someone has to be stupid.