The original Dr. Smith was a coward, funny, untrustworthy but for all his faults the audience could find him likeable.

The movie Dr. Smith was more or less a terrorist, smart, and evil. One of the better actors of that movie, so it worked.

Now for the Dr. Smith of the TV series (2018): Underachiever that will stab anyone in the back and does it all the time. She is the stereotype of a drug addict, and no charisma what so ever. It is probably not the actress fault, just bad writing.. Killing her off could help the series, but a "lost in space" without Dr. Smith? No that will not work! She could get possessed by an alien entity. And change this horrible personality for something more likeable.