There's multiple reasons why Clam Blitz is disliked. It is mostly disliked by the veteran players who've played Splatoon 1 and are used to their three awesome modes (SZ, RM, TC).
At first I thought it was just disliked because it was something new and the vets were annoyed 'cause they were as new to a mode as any other newb and it would be a long time to get good at it and define the meta etc. etc. But it wasn't that, to my knowledge. Most of the people I know, including myself, don't enjoy ranked Clam Blitz because CB, in itself, is a game mode that requires high team coordination and synergy by nature. More than can be achieved in a team of random strangers with no means of making contact with each other. It goes beyond what is likely to work well without voice chat team coordination. And since you have no means of making contact except for "Booyah!" and "This Way", attempted order and coordination in strategy are most oftenly killed in their very begining.
This is what really stops me from enjoying this mode a lot. Others may feel differently of course.
Why you feel different right now is simple though. You are, as you said, B+. In that area, there are a lot of newcomer players so it is significantly easier to make a difference and pull a whole team to victory. At B, there isn't much of any coordination going on. But since you seem to be decent at the mode, as you said that you win most of your CB games, you may quickly advance upwards and notice what I am talking about. At S+, skill levels are way higher and even the slightest plus in coordination can decide over victory. That can be quite exhausting. I feel that is what a lot of players agree on...