Not as important as you think. If this were the case, we would have seen more teams using pneumatics in the past when the rule was 8 motors + no pneumatics or 6 motors + pneumatics. There’s definitely a minimum number of degrees of freedom and I’m not sure where that number is, but power is still king.
Especially if you consider that in the past, had you decided to go 6 motors + pneumatics the extra DoF you’d gain would have diminishing returns. Since every actuation releases pressure from the system each time you actuate you have less and less force until you eventually don’t have enough force to move your mechanism.
I think you’re exaggerating what these locks would look like a little. There are lots of examples of semi-passive locks out there. Is this something any team could make? No. Is it something that only a handful of teams will be able to do? No.
Every year I’m completely blown away by the passive/semi-passive mechanisms teams come up with to make their robots fit in the sizing box, give their robot an extra actuation, etc… VRC teams are actually extremely creative in this regard, I would argue, more so than teams in other competitions.