I don't have the feeling that people don't like coinbase. But depends on experience they have. Some of them had problems with customer support or bad experience with freezing accounts which could be very annoying.
For sure that base on the experience of other people like this one
https://bitcointalk.org/index.php?topic=1651233.20 his coinbase account was hacked.
I don't know if those people are just negligent for their own accounts or does the support of coinbase has something to do with its security.
But for me, I don't have any other reason. I just don't like coinbase.