First, yeah it is a bit long especially if you are doing alts. Buuuut, the storyline between Praetorium and The beginning of Heavensward is the prologue for Heavensward. Without it you don't get to know Alphinaud or really most of the characters that become important in HW and Stormblood. Just like skipping the post Heavensward stuff would erase half of the set-up for Shadowbringers. Though that also gets started in the post ARR quests. If story is important to you I recommend just doing it. Sidequests not so much. They add depth to some things, but they do tend to keep the important stuff in the MSQ.