I don't think there is a blame to put on app-makers. The Apple Watch is a companion-product by design.

Apple's target-group for the Watch is every iPhone user, they know that with patience they can sell an Apple Watch to every iPhone user out there.

So there's little incentive for Apple to create a Watch that doesn't require an iPhone, and little reason for app-developers to assume you own a Watch but NO iPhone...

I agree. The Apple Watch is very useful, but I'm not happy about having to buy an iPhone to go with it. With luck the Pixel watches might become good enough to replace it.

The problem is: how well can you interact with a phone the size of a watch? I mean, for some things, yeah, it works fine. But other things? There's a reason why phones have been getting larger (no iPhone Minis anymore). Even Android side, expect Google to always assume there's a companion phone available, because the interface for adding in info will continue to be terrible, simply due to form factor constraints.

Watch projects a screen and gestures.

This is more convenient than carrying a phone, is it? Gonna project your work on the wall of the subway on the way into the office?

Or glasses get small enough. Gesture and voice will continue to improve. Apple Vision Pro (and other AR devices) will continue to improve. It's not hard to see a path where today's phone format goes away and/or becomes used only for certain situations.

Voice.