On a spunk scale of 1-10 with 1 being a protection and 10 being Cass from New Vegas, Curie is like a 2, Cait is a 8, and Piper is probably about a 6.5.

Nobody will ever replace Cass, but Piper's probably my favorite of Fallout 4's gals.

Point is while she is in the vault she has no reason whatsoever to even think about smoking or do any studies regarded to it, its not her mission objective(her expertise is contagius diseases-most likely bioweponary as well and neather of those has anything to do with long term side effects of smoking) now once she comes out of it and migrates to new body there is still no reason for her to even think about potential long term hazards of smoking, first of all in the world as it is smoking wud be very low on the list of priorites for any kind of resarch about it in forseable future.

Point is you are applying real life logic to imaginary exaggeration of future 50s style America, smoking in the game isnt considered bad nor was it considered bad before the nukes hit. (pre war Fallout is basicly a world of exaggeration more or less everything is nuclear powered, large corporations dump toxic/radioactive waste in the local ponds, goverment is corrupt, most popular soda drink has radioactive isotopes in it, hell even boardgames have nuclear material in it, drug usuage is common, in military performance drugs are even required/encuraged basicly its an exaggeration of corporate run state where one and only thing that matters is the bottom line so compared to all that smoking is rly a very minor thing anyone in such world wud worry about. (but yeah sure i agree the technology to find out that smoking is bad for you was available before the war but same as with all other health hazards in that world, corporations made sure that never got out since it wud cut into their profits)