You may find yourself in that situation if you have a device that only supports SIMs, and you can't use any of the cheap travel esim providers with it. For travel, you would replace your local SIM with the 9eSIM, and be able to switch providers depending on destination. The difference can be huge in some countries, where a local provider's travel plan can be 30 to 50 USD, while a equivalent on an ESIM provider is just $4.

I live in such a country and have parents with older phones who can't use esims, so the value is obvious to me. :)

One announce with eSIM is that you can’t move them freely, despite being advertised as equivalent. Depending on the provider it can get quite complicated (physical visit in store, fees) to move to another device.

Chinese iPhone has no eSIM support (they have dual SIM instead), IoT stuff like alarms tend to use SIM slots, LTE/5G routers tend to use SIM, etc.

Until eSIM provisioning for embedded devices is sorted out and popularized there will be plenty of reasons to adapt to a regular SIM.

I can't speak to anyone else, but I have a phone about a year too old for e-sims to have been commonplace, but I still need to travel, and services like airalo (global sims to go) are basically e-sim only -- so my secondary sim slot is a reprogrammable eSIM.

I got a second hand mobile router with SIM support, but very good hardware for 50$. I ordered a Esim adapter SIM for $20 and just switch to the cheapest network wherever I am.

Easily saved $300 to a comparable device with Esim support.

quote from TFA "Since I want to use the SIM with the integrated WWAN modem of a laptop running Linux, I was keen to see if I could get this all to work using Linux and Free software."

Well, one nice thing is that a device like this allows you to use the services that are trying to lock you with an eSIM in the same way that you use a normal consumer friendly SIM.

Simply there are more eSIM providers than traditional SIM ones, so there's more competition and lower prices. That alone is enough.

Yep, it isn't as if there aren't cheap pre-paid throway SIM available as well.

Let’s say you land in a new country that your primary provider won’t roam to for free or at all, there’s no need to visit the airport shop that sells SIM cards with limited options and try to buy and set up something which is often in a different language.

You can buy your eSIM service at the best possible price ahead of time online and have it ready to go when you land, and you don’t have to upgrade your not-that-old phone to do so.