While I criticize Sakura for her shyness it's not shyness I hate. Personally I'm shy and I can understand the experience of being shy. The problem is when that shyness and that reservedness is used as a tool to make the character bland and use that shyness as either justification or pandering to those who like reserved girls. I don't mind shyness when it's one of many traits that a character has. But when it's the only trait, it gets really annoying.