Since way back in the 90s, everytime I stayed somewhere for longer than a week (or I really really needed mobile data) I would simply buy a local pay-as-you-go SIM for it.
This has been made even simpler to do with the advent of dual SIM phones were you can have a SIM for calls with your personal phone number and a different SIM for data.
Further, here in the EU ever since they passed some legislation some years ago, mobile operators can't charge extra for roaming within the EU so none of that is even needed anymore if you're just travelling withing the EU.
What exactly is the great advantage of eSIMs if you have a dual SIM phone?!
In some countries it’s not easy like walking in to a store and getting a prepaid card. You need to have an ID and a local address, probably to prevent bad events which use sims cards. A travel sim could be easier but more expensive.
eSIM is much easier and can be activated using an app.
Yeah, I wanted to do this in Iceland a number of years back, and they needed a local bank account in order to open one.
My Icelandic father-in-law helpfully offered to put it on his own bank account, saying he'd just cancel it at the end of the month. This was acceptable. Gave him like £10 to pay for it.
Went back two years later. You'll never guess what he'd forgotten to do...
What exactly is the great advantage of eSIMs if you have a dual SIM phone?!
If the phone supports a normal and eSIM at the same time, they are equivalent. Because in many countries, dual SIM phones are (and will be) harder to get than single SIM ones, so having eSIM at least allows that.
You can have as many esims as you want too, so you can have 10 numbers or data packages if you want. Just open the app, buy one, install it and it's ready to go, no need to deal with phone companies.
What exactly is the great advantage of eSIMs if you have a dual SIM phone?!
eSim means you don’t have to go to a store to get a physical SIM. You can use a ‘SIM store’ app to get an eSIM for wherever you are.
Another minor advantage is that you don’t need a SIM PIN as the SIM is a physical part of the phone. So you only need to enter one code when you restart your phone.
That's like saying that the advantage of DRM in media files is that consumers are forced to use it.
The only advantage for consumers I see for eSIMs is that they can be bought online and digitally delivered, so mild convenience, which is nice, but not quite as amazing or filling a great necessity as the OP tries to make it sound like.
Beyond that, well it creates new business models and is probably cheaper for mobile phone makers, which are advantages for others, but not for consumers since the barriers to entry in the mobile arena that make it prone to cartels aren't in the provision of SIMs, they're in things like radio spectrum licensing so eSIMs aren't going to cause a price revolution in that market.