Notice how you even said "all the major carriers"? What about the not so major ones? An e-sim would prevent me from ever using the device on their network, resulting in fewer choices for me as the customer.
For people who like to swicth devices back and forth, like I do with my phones, it is not convenient. It takes me about 2 seconds to switch a sim card from one phone to another.
Also, when traveling internationally you can't just put in your foreign SIM (which is what I do every time I travel, right before take-off). Instead, you have to figure out what number to call after you land,and how in the world to communicate with the person on the other end if you don't speak their language. All this possibly while on a crowded plane, incurring roaming charges.