People _love_ Taco Bell in America. Why? Because it's healthy? No. Because you get a large portion of food? No. Because you know the filling is even? Nope.
Why can't people come to Japan and love conbini sandwiches for what they are? An easy, cheap meal.
As someone who isn't a breakfast eater and actually dislikes Toxic (lol) Bell, I love visiting Japan and getting to grab a quick breakfast or morning snack for dirt cheap. A tamago sando, plus a hot bottle of tea, really warm me up and get me going for the day in a different place.
Sure the MSG that is likely in the tamago salad helps matters, but why's that an issue?
It's odd to see.
I have made several friends in Japan who are locals, and most of them enjoy their conbini food as much as I do and are surprised when I show them what we get (or explain what we don't get) here in the US at our convenience stores.
It seems lately that there's this anti-foreigner hate thing going on, mostly by expats (?) where it's like non-expats aren't allowed to enjoy things that are common in Japan or something. Clearly in general, sandwiches there are good because otherwise they wouldn't be such a popular item that even many locals will grab on their way to work or a picnic or...
Again, mind-boggling.