Sorry, I never meant turning them into hybrid, I just meant upping the defence against sharp for the case where you leave your units exposed - 1 is really really weak.
I agree, horsemen are great offense units.
Also comparing them to chariots is not a good point of comparison imo. For one, chariots are a hybrid unit, so they will be built more as some use them in cities they don't want to specialize for a reason or another, or because they don't plan on being online for example.
But also, chariots are mainly defence and horsemen mainly offence, so they shouldn't be compared against each other, defence and offence are usually organized differently. For offence, only the value of the units in one attack count, so a lot of players will favor attacks that mix the three weapons. For defence, all units count, so it doesn't matter whether they are built in the same city or not. Also both other main defence units, swords and archers, don't use stone, which leaves chariot as a good way to use resources in your defence cities. Basically, I am saying the reasons that chariots are being built have nothing to do with the reasons horsemen are being built or not built.