Exactly. It costs a lot of money to run a bullet train, and every seat is very valuable. They don't have space to waste on a kitchen or restaurant. They do sometimes have little food carts they'll push up and down the aisles that you can purchase meals from, though this depends on the route and time.

Riding a shinkansen isn't like riding some old-time long-distance train in Europe or North America; it's basically just like riding in an airliner, but on the ground and without TSA and the seats have more legroom. It's all about speed and convenience, not luxury.

There are, however, some luxury trains in Japan on some routes. They're not bullet trains though, and usually meant more for sightseeing travel.