I have a plot question! So, I've looked around the internet to find answers to various questions I had and just better understand the story that was told. But there are a couple of things I can't wrap my head around.

1) Are the royal arms actually important to the story in any way?
I mean you have to go and collect them but there doesn't seem to be a reason for that other than "these are super strong".

2) Are the Astrals actually important to the story in any way?
So, you do the trials to get the power of the Astrals. But... this doesn't seem to actually do anything other give you the ability to use summons in battle occasionally? Noctis's important power is not related to the Astral's power at all, and it's awakened by Luna in order to defeat Leviathan. So beyond Bahamut being the person who reveals some plot details to you at the end, I don't see how they are actually important to the story in any way. If you took the Astrals away the plot could remain basically the same, couldn't it?