I don't go for the fatty meat sandwiches, either, and some of the pictures people take of their corned beef or pastrami or brisket sandwiches are positively gag-inducing with the slabs of fat in them that would be so easily removed.
When I make my corned beef here, I'd guess that what I eventually serve after all the trimming would have to be termed EXTREMELY LEAN in restaurants and would therefore cost a bloody fortune. In truth, I probably go a little too far with that, even for my own taste. I know you need a certain amount of fat, for moistness and flavor. When eating, say, a steak, while I'd never put a hunk of fat into my mouth, I do know how a tiny bit as part of a bite of meat can be a good thing.