My general impression is that tracking protection is low-priority for Mozilla and anyone who actually cares is using uBlock Origin / uMatrix or similar extensions since those use filter lists that are actually updated.
It is on by default, and as you point out, breaks many innocent sites. People may migrate elsewhere. That should bump up its priority.
My general impression is that tracking protection is low-priority for Mozilla and anyone who actually cares is using uBlock Origin / uMatrix or similar extensions since those use filter lists that are actually updated.