There is definitely depth to the combat. I think all of the unique passives and sequential effects really add up. Do I want to use my last skill point on a buff that lets my DPS unleash an unholy combo, or should I heal now? Etc etc
This ultimately ends up addressing what other commenters here have said about not just mashing "attack" forever in final fantasy. If you just use basic attack in Honkai Star Rail, you will mostly lose and sometimes be there for hours in a single battle.