Basically there's two parts to the scenario of why things play out the way they do.
First thing, is the reaction animations ended up being toned down or taken out in parts to stop players going out of their crease. This was done fairly late in development as we found that situations were occuring too often where players that were getting hit would either walk out of their crease or end up out of their crease and be given out.
As for injuries, they take circumstances of stamina and being hit numerous times for an injury to occur and even then the chance would remain low. Due to other circumstances recovery happens quite significantly between innings as well, so I'm not overly surprised people haven't quite found it.
In the end, injuries in cricket (during actual physical match play) tend to happen very rarely as is. We'd need to ensure, that if we looked at increasing the rate, that it isn't done to the extent that injuries occur every match or even few matches as that wouldn't exactly be helpful.