I think they've got a fair point, though, that a number of those issues with the eSIM reflect reliance on factors outside their control (for example, whether or not one's carrier has competent backend systems) where before swapping a SIM card was a physical action within their control. It's a frustrating feeling when a new technology takes something out of your hands in the name of convenience but, far from being seamless, actually introduces problems that are entirely out of your hands to fix.

The carriers are the problem, though. In many countries there's at most one eSIM carrier, some don't allow it for pay-as-you-go and their implementation is often generally poor.

There's very little a carrier can get wrong with a SIM.

I wasted a couple hours dealing with the fact that my carrier wants an ICCID to activate an eSIM, but iPhone eSIMs don’t have (or at least don’t show) an ICCID until after activation.

My carrier literally has a webpage explaining how to do it on an iPhone, and the page is blatantly wrong. Good job testing.

Does this ID change if you provision a new eSIM? Would it be worthwhile to activate an eSIM on my phone and write down this ICCID for safe keeping in the future? Is there any other way to get this ID without having an active eSIM?

There is an ICCID, that is usually burned into the eSIM. However, SIM and eSIM are actually a tiny embedded system with a rudimentary Java byte code interpreter and you can insert firmware to dynamically swap between the reported ICCID. Usually this is a trick employed by MVNOs to swap between profiles based on the available networks to select the MNO that the MVNO has a more favorable contract with.