Being honest and being blunt are two very different things.
Just because you CAN tell it how it is, doesn't always mean that you SHOULD.
Honesty, and especially sincerity are wonderful attributes, but tact is equally wonderful.
Tact is sorely under-utilized in our society.
Patting yourself on the back for always "telling it like it is", even when unnecessary and insensitive, doesn't make you look cool; it makes you look rude, dumb, AND pretentious.