TBH I wonder how you used your cav before this change...
for me if I had 5 unis of cav I could sweep the field in 3.2 and take out half the standing army of my enemy with tactics..
the other half would ussually be engaged with my infantry which won me battles.
Cav were powerful in those times but they were not THAT powerful. The reason the mongols swept those regions is because those same mongols were VERY experienced fighters. It is like sending in marines compared to Army. They got the same gear, it is the tactics and the ability that makes the difference.
Cav were VERY powerful before this change...now it is just out of whack.