My problem is I don't really have an off-season, nearly all year round I go on at least one hike a month that's outside of cell coverage (not too hard around here), which is why I got the InReach in the first place.

is 15$ a month really that expensive when it gets you the ability to communicate anywhere?

It's not expensive when it's compared to the alternative of not being able to call for help when there's no cell coverage.

But it's expensive if it's compared to $0 for a feature that's already built into my phone. (though it remains to see how long Apple keeps it free since they only say it's "free for 2 years")

afaik the new iphone is SOS and location only, no text bridge

There is a $35 annual fee for the ability to turn the plan off and on.