My family is Mormon (or, more particularly, Latter Day Saints etc), and I was for 14 years before I bailed out -- my family is sad about it to this day, and maintains that I will come back into the Church. Who knows?
I think it's insensative to do this, but, at the same time, it's the entertainment industry. It's about getting numbers and telling a story. Even if I was an every-day mormon, going to the temple, etc, I don't think I'd change my opinion on the matter.
Fact is, secrets like the "endowment" don't stay secret. The church knows this, and anyone who's getting up in arms about it is worried they'll look "bad."
Mormons shouldn't get upset about this. If we're willing to dish it out (and we are), we gotta be willing to take it. OMG religion wars amirite!?
I'd love to download an episode of the series to see how faithful it is, seeing as how I live in Utah, and it'd be fun to see their take on the day-to-day bits.