I agree if you plan to use iPhone for less than 2 years it's probably expensive.
The official situation is slated to improve now with Android 8 separating the HAL and the rest of the OS more clearly it likely means that in a generation or two this won't even be a concern.
You see, right there you described why most people, myself included, aren't interested in that. I can't be bothered to care about weekly OS updates, I tolerate the 1-2 yearly updates to my android because as someone in the security industry I understand the need for updates but that's it. A phone isn't something I care about tinkering with, it's a tool and I want it to work well with as minimal maintenance getting in the way as possible. I couldn't even be bothered to root my current phone, much less install a different OS.
We're not talking about major updates here, we're talking about updates that take about 30 seconds to apply plus a reboot, once a week and you know you're always running the latest and greatest from a security standpoint. Most change nothing from a user perspective.
Of course, you're free to treat these updates as you like, I typically only patch about once a month or when there's a major remote vulnerability.
Like I said, doing weekly or monthly updates and reboots would be an extra concern that I'd rather not have. As it stands the only "management" burden my phone (I use an HTC 10 for reference) imposes on me is having to connect it to the charger every night; It's already more than I would like but unfortunately it doesn't have wireless charging.
As far as I'm concerned, for non-hobby stuff, the least management a device asks of me, the better it is because it's a few more things I don't have to bother taking care of.