Battlepasses are a retention mechanic. I completed the last one in 2 weeks at most (pretty sure that means other/better pirates were completing it in days). Season 8's seems to progress at the same rate as the last and is the same amount of levels (100). Its not going to retain many players for 16 weeks, now is it when the last one was left available for too long (IMHO) at 8 weeks...
I get it, hardcore players always chew through content much quicker. But that's why most games with a mature Battlepass feature set include an infinitely earnable level 101 reward.
I hope the team is looking at the data and seeing things that I can't, to justify this approach. However I suspect they are setting Battlepass length simply to time with their next content updates & calling it good :(