Mark my words, this is coming. Once RAM is cheaper than having multiple production lines, you'll buy phones with RAM that is disabled and you'll have the option of enabling it OTA.
But the possibility to replace a SIM if defective without replacing the whole phone is an advantage. You can also swap sim really easily when travelling.
Sorry what? It creates a door, which needs to be sealed for IP rating, which needs to be located in physical relation to the edge of the phone body, needs power and data vias routed to/from which dictates the location of the radio, antennae etc. etc. etc.
It's absolutely impactful to the electronics design no matter the screen size, you just can't see all the decisions and compromises associated with it.
Yeah, I didn't think about the amount of tiny little parts it needs around it. But what I meant by that is that once a phone gets wasted, all the micro-tiny cables and plastic SIM door and the SIM's collective weight and volume are quite minuscule, compared to the phone's weight and volume. It's an improvement, for a fact. But is it really worth gutting that phone of the SIM slot for such a tiny improvement?
What network and where? Many (the majority) networks offer it for free. There is talk of regulation forcing it to be free to download too, and it can't come soon enough.