Yes it does matter, if the official story established by the Warren commission is not true, it does matter to know why was Kennedy assassinated and by whom exactly, because Kennedy's death has had so many worldwide implications, that this isn't even just about USA.
If that story is ever debunked one day, factually, it will change the future of the USA. If the government lied about all that, then what other things the US government lied about? It will shake the very foundations of that country. It's literally the definition of a smoking gun, no pun.