I personally couldn't do it since the Watch and iPhone are COMPLETELY different devices filling COMPLETELY different purposes, with some occasional overlap. For example, I could NEVER use the camera system on my iPhone on my Watch, nor could I do more productivity things like file management, etc. which is crucial for work! Also, you can't do FaceTime/video conferencing on your watch, nor would it be a pleasant experience if Apple were to put a front camera on it, for some reason.
However, I do get what you're talking about to where the Apple Watch, in certain situations and use cases, could replace the need for your iPhone. For example, whenever I run out to do a few errands, and I don't need to use my iPhone's exclusive features, yeah, I'll leave it behind and just wear my Apple Watch. One thing that I can't wait for Apple to do is to make the Apple Watch completely independent from your iPhone so that you can set it up without one. When that day finally comes, that'll be a BIG step for the Apple Watch being its own device!
However, I do get what you're talking about to where the Apple Watch, in certain situations and use cases, could replace the need for your iPhone. For example, whenever I run out to do a few errands, and I don't need to use my iPhone's exclusive features, yeah, I'll leave it behind and just wear my Apple Watch. One thing that I can't wait for Apple to do is to make the Apple Watch completely independent from your iPhone so that you can set it up without one. When that day finally comes, that'll be a BIG step for the Apple Watch being its own device!