I don't like being blunt. I feel you can be honest without completely ignoring social norms about what's offensive and what's not offensive and without just saying what you want to say whenever you want. Yes, it's easier for the person saying it, but from my own personal experience I find it much more annoying/offensive/hurtful if I feel someone doesn't even have enough respect for me to care about what I think, so they just say whatever insulting thing pops into their head under the umbrella of 'blunt'.
There are ways that things can be said that are both honest and avoid hurting the other person. Take for example, the criticism sandwich that many people use when criticizing a work. The people reviewing don't change the actual criticism that they're making, they just put a compliment before it and one after it. The first one gives the creator some confidence in their work so they don't feel like you have nothing nice to say about it. The one after the criticism reminds them that you're not telling them that because you want to hurt their self-esteem, but because you like the rest of their work and want them to grow to be the best they can be. The person who does that gets the same point across as the person who immediately jumps to "This part sucks and I hate this part", but in a way that doesn't actually hurt the other person.
I wouldn't say I lie to people to make them feel better or curb what I'm trying to say, but I do try to put it in a way that won't hurt the other person. Kind of a 'treat others the way you would like to be treated' thing for me - I would like people to care enough about hurting me that they put more than a half second's thought into the impact of their words, so I try to find a balance between telling people things as honestly as possible without doing it in a way that might be offensive or hurtful towards them, haha.