Maybe people just don't like being told that their moral stance is less strict than yours when they don't feel they're doing anything wrong. Your post is almost literally asking, "Why are people upset when I have a holier-than-thou attitude?" What is really the difference between, "I have chosen a stricter moral stance," and holier-than-thou?
This makes your point... I just find it incredibly odd.
Correct me if I'm wrong, but you're saying that when you say "stricter moral stance," you mean "more rules." That is not how I would interpret "stricter moral stance."
I suppose I'm also thrown off by the concept of "my morality." If morality is entirely personal, the whole concept of stricter or looser moral stances seems nonsensical. If it's entirely personal, then isn't everyone, by definition, strictly adhering to their own morality?