That's not true at all. Back when tubes were in everything most electronics were wooden boxes. They get hot but they don't get hot enough to set things on fire in normal use.

In this day and age most of the draw of using tube stuff is how it looks, not how it sounds. That's why basically all new tube stuff has them up front right in the open. Back when people used tubes because they had to they were almost always hidden inside, since the glow was an unwanted side effect.