It’s smart to do it first year, not every year. Your kids, like mine, go to schools where it doesn’t matter. But there are some where it does matter.
it’s personal preference, but if a child is applying to many schools and hasn’t yet picked one out, it’s a good box to have checked off just in case. For example, one college, I can’t remember which, offered a $1K scholarship just for submitting your FAFSA. Others on other threads have mentioned that a select few schools require a FAFSA before they’ll award you merit aid.
But if one chooses not to, that’s fine too.