The cost of "educating" a TV isn't that high. Certainly less than the cost of a streaming stick or box since there is less or no additional hardware needed in most cases. Leaving it out of a higher quality TV limits the potential buyers so they all chose to include smart apps.
I also prefer to use an external streamer because I can chose which one I like and can update and change it when they improve. It does tend to make the user interface a bit more complicated than just selecting an input.