A few botters don't hurt Pokémon go. But when it's easy to bot, lots of people will bot. It's easy to circumvent anti root, but it's impossible to use the same way for lots of devices without niantic being able to block it again.
So it really makes sense for them to go this way IMO.
Not really. It doesn't matter if the phone is rooted or not, what matters is whether it is feeding false gps data or not. Bots will soon find a way around this (non-rooted) restriction anyway.
That said, proper protection against cheating would involve using markers (other phones?) in vicinity, so it should be possible too.
Yes, bots will most likely always find a way, but I think it's more about thwarting the casual users. If you could gps hack by simply installing an app more people would do it. By making it extremely tedious, the causal user won't be as inclined to do it since the time it takes to figure it out won't be worth it.
I don't condone Niantic's behavior, but I understand it.
To me, it would make more sense if they weren't also banning users their auto-detection system thinks are spoofing GPS. A system which is fairly overzealous, might I add. I was banned for being in Japan, for example. One day out of the blue on my vacation, got the ToS violation notification which still hasn't been reversed, two weeks later.
The spoofers have had a way around this for some time now, as GPS spoofing simply does not require root privileges.
Niantic is not actually making any attempt to look for GPS spoofing software. They simply invoke Android's SafetyNet which doesn't care about GPS at all but does care about other things which happen to coincide with what's on some cheater's phones. It will never be anything like an effective measure against GPS spoofing.
So it really makes sense for them to go this way IMO.