You would still buy a Macbook if patents and copyright did not exist, wouldn't you? In fact there are much more powerful designs in the PC world. But you stick to the Apple brand because you've been burnt with everything else, from cheap knock-offs to famous makers who distribute an OEM versions of Windows with viruses and rogue root CA certificates. What saves Apple is being the only make you can rely on. They're not particularly innovative in the products they make. What is the role of patents in that?

Without copyright, anyone could make a knockoff Apple and it would dilute their brand so much as to make it unworkable for Apple to make a quality product and get paid for it. Apple absolutely requires copyright protection of their software to keep their brand exclusive to drive profit to keep making nice products. The PC world that you noted is the epitome of the race to the bottom they would have to participate in otherwise.

I disagree. The race to the bottom you observe with PCs is largely caused by the same lock-in forces enabled by strong copyright.

In your hypothetical example world, Linux would be on equal playing field when it comes to video/hardware drivers. So it could compete as a serious gaming platform. Without vendor lock-in, hardware would have to be more interchangeable, so can select their own choice of hardware, which can be cheap or expensive or powerful or quality or pretty etc and fit it inside an aluminium casing if they like. They could get a matte screen and a nice keyboard ...

Without Apple's market power behind it, nobody would consider using iTunes over a normal mp3 player.

There is demand for pretty computers, powerful ones, durable & sturdy ones, et cetera. That won't change without Apple. Sure it won't offer the exact same things Apple does today, but on the other hand it will provide a whole bunch of things that Apple today doesn't or won't. On the whole it will be neutral or positive.