Yes, humans didn’t evolve within a state of having months of prior interactions, so it seems pretty unnecessary for normal interactions. in some sense the expectation of having forever data is created by or at least subsidized by the benefit of the platforms mining that data for something they can sell of you. 

 Spot on!
Personally I often prefer setting chat services to message decay / dissappearin messages. Always feel chatting becomes more natural after that. :)