You have a point here. Kosher delis were almost always better than non-kosher. By their very nature, quality control and supervision was more stringent. This usually (but not always!) translated into a better product.
As far as health, I hear this argument a lot and I just dont see it. If health was as big a motivator as people say it is, then fast food chains should be disappearing as well. We all know that it is just the opposite.
I have maintained my weight since college, and do not deprive myself. Its called exercise and portion control and you can eat pretty much whatever you want. Do I have deli everyday? Nope. But if there was a decent deli by me, once a week would certainly be my frequency.