"Defense is not something that can be quantified well at all. "
That is not what the pro scouts in the NBA think...
Defenders that can shut down a good offensive player like Kobe are scouted and play a role all the time.
Pro scouts in the NBA, and the NHL are able to come up with useable metrics for defense: why wouldn't the brain power of FRC want to do the equivalent?
How could a good scouting/picking team decide if defensive pick is better than another offensive pick if the scouting team has not come up with tangible metrics for defense centric bots?
If the only tangible collection is of offensive metrics, then the data would naturally bias those using it to pick three offensive teams instead of 2 offensive and one defensive.
I've only been around FRC for three seasons, but I've looked at videos from previous years as well: consideration of defense seems to be generally an afterthought by most teams until it's shown to be effective.
When defense is effective, there are tangible metrics to describe the effect. The question is, will scouts look for them?