Personally, I really like the fact that, most games nowadays that have different difficulties, have an easy mode.
Whenever I get a new game and play it for the first time, I always play on the easiest setting first. That way, I get a handle for the controls, can really get into the story, and generally have a lot of fun. After, I may bump it up to normal, or if I'm wanting an unlock or an achievement, higher than that.
But, generally, I play campaigns on easy. Why? Because, when I play a campaign, I usually want to chill, have some fun, and not get extremely frustrated like I do with some multiplayer.
Anyway, if someone else decides to play on easy, hey, that's up to them. It doesn't make someone less of a gamer.
What doesn't make any sense to me is when some people play a game the first time on the hardest difficulty. Or worse, they do that, then get pissed and frustrated because it's too hard.