i mean, i absolutely understand that storytelling in a movie is very different than storytelling in a book and you can't have a 1:1 translation between the two. and like i said, fellowship is my favorite movie of the three.
it's just that there are things that are missing and/or done differently that don't REALLY change fellowship much at all, but have a big difference in the other two movies. there are changes in how certain characters behave and/or relate to aragorn that FEEL like it's not really that big of a deal, but make pretty significant changes once you look at the whole. there were no other rangers in fellowship, so they weren't there to aid aragorn in helm's deep. on the surface that doesn't feel like a big deal but there was a whole cadre of rangers that were secretly moving against sauron's forces and when they get wiped out it puts the legacy of the dunedain all on aragorn's shoulders and helps the audience understand WHY aragorn is the way he is. it's not just his heritage, which makes him the rightful king, it's things like losing all his kin that help him understand sacrifice and the weight of honor that make him THE RIGHT king.
i mean, let's also mention that in the books, aragorn never hemmed and hawed about his destiny. he accepted his fate as the true king some 60 years prior to the events of the books.
again, i understand you have to make changes in order to set the right pacing, just that while a lot of these changes seem minor and even make sense in some lights, they fundamentally altar the intent of tolkien's work. aragorn and the elves NEVER doubted their work against sauron even if they doubted the outcome and the message that you do the right thing because it's right, not because it's easy, gets somewhat muddled.