Right.
Making them just more expensive wouldn't help much, from two reasons:
1st: everyone should have the chance to use cavalry, if he wants to. This doesn't mean he automatically gets better in the game, so I think a stat nerf according to the few thousands you have to pay would be justified. (And, if you look at it properly, if 80HP or 60HP doesn't make a real difference, with the speed bonus for attackers your horse will be dead anyway from a pikestab/swordslash. Also 2-3 points speed less don't change much). A simple reason why the stats deserve to be nerfed, despite any value calculations or whatever: there are too many light horses on the servers! You have to nerf horses until you reach a horse population on the servers which is acceptable. If after some time the population gets too low you can buff them a bit again, then nerf them, and so on, until balance has leveled out itself on the ideal niveau.
2nd: making things expensive doesn't really balance them out, I think. The patch was meant to stop those tincans on plated horses, but if someone saves some money he can play as heavy knight for some rounds. For the other players who have to deal with him nothing changes much. If he is actually on the map, what do you care about that he will be able to do this only for the next few rounds? Currently he is there and is collecting cheap kills. And as soon as he runs out of money another guy puts on his plate. And no, the patch didn't minimize the overall number of (heavy) cavalry on the servers, as the cavalry players are alternating now in their lolstomp, because of the simple fact that with the new money income much more players can purchase heavy equipment.
Before the patch we had 10% of the players playing 100% of their time as heavy cav. Now we have 30% of the players playing 33% of their time as heavy cav. Both is 10% heavy cav on the battlefield. (Don't argue about the 10%, could be 5%, 12% or 2%, don't know. Just felt values.)
This is the reason why I think that in most cases a balancing by price does not really eliminate problems. The stats decide about how many players want to use an item, not the price!