Because `iPhone` was a super unique name...
I would argue that people are not excited about Apple TV because it does its job. There isn't a major need for new features but if they find a good feature to add to it, it can cause excitement.
The OP is right though, the Apple TV being able to be a hub (which also means it processes Secure Video and how you access your HomeKit devices from outside your home) is a nice features that shouldn't be discounted. It is a Hub that is already in many people's homes and could be a gateway product.
I guarantee you that if Apple announces a new Apple TV with some fantastic new feature, more people will be excited and buy it than there are that follow HA updates.
The Apple TV is my favorite. It’s also the one that gets used the least. Because it’s one of the older models that has the glass remote and we drop the remotes all the time so it’s only used when I’m the only one watching and I generally control it from my iPhone (only iPhone in house). And it’s so much more expensive than the others. One Apple TV costs more than the others I have, combined.
At least there’s a few geeks like me who’d be excited about a new Home Assistant update.
But literally no one cares about Apple TV, a product so uninteresting that Apple couldn’t even give it a unique name.