I don't know... I would be more than happy to buff chamberblocks if punishment for failing was harsher. Specifically, the kind of failure that just transforms your chamberblock in spam. Chamberblocking on purpose makes feints nearly obsolete, so they are not really enriching the gameplay that much, giving something while taking away something else.
The core problem is that chamberblocking anything but slow overheads is much too risky for brittle agi characters, so they won't do it anyway. The time windows are so short, you are bound to fail at some point. Even if a chamberblock can help you kill your opponent faster, you won't do it if failing means dying. That's not the case for high armor high str characters.