Characters are unlikeable because writer is unlikeable
Lena injects herself into these obnoxious characters. She thinks narcissism, entitlement are funny because it's how she is. Just caught the HR Roundtable where she likened her mother to the "Jewish Diana Ross " and cracked a few inappropriate jokes about Gina Rodriquez's grandma buying crack with her money and moving to Atlantic city. She embodies all that is disgusting in her community. This is why people hate her and this show. It's a shame. Because some of the writing is brilliant. Her acting is often exceptional. But the problems with Girls are the very things right with it. Lena herself. She is a liability. She needs therapy and the show won't provide ot for her obvious untreated mental illness. Before you condemn me, I'm a woman of color who is not conservative at all. I just don't like Lena's brand of neurosis.
Someone on the writing team should check her otherwise I fear for season 6 being another Hannah obsessed mess.