I guess that SE decided because tower sheilds offered much more in block percentage, that they should also offer the least amout of offensive capabilities. Honestly, removing the stats off of sheilds would likely result in only gearing with scutum's in the future. It is an extra 8% damage mitigated on a singular attack every 30 seconds (basically it's foresight, on demand).

This is the one area where I refuse to min/max for offensive potential. The difference between the ThorEX shield and the upgraded ESO shield is 3 relative strength (this is also the same split between the ESO+ and Gordian). I am willing to sacrifice 3 strength this one time for that extra mitigation.

I don't believe that it would be balanced if all shields only had block rate/strength on them. I don't like the idea of having the best of both worlds, because there is no real choice, you would simply go with the biggest blocking shield.