Originally Posted by
Buffalobiian
It's for a few reasons I think.
For one, we expect that a person who has no special skill aside from having lived in the modern age to be able to cook to a degree. You'd have to take a Dr Stone protagonist to be able to improve other aspects of people's lives. It's hard to be like "this is manga" or "this is television", but "this is pizza" is relatively believable.
The delight is also something I guess we understand - like seeing other people pet puppies. We can imagine a world without pizza, and that's not as nice as one with etc.
In the end though, I think it's an easy way for a lay modern person to do something nice for a backward society. The satisfying reaction from people eating pizza is also something we can readily appreciate.