Catas and cav are pretty worthless for a couple of reasons

One, catas and cav just beg to die. They can not survive anything. You can outnumber an enemy 5 to 1 and still take heavy cat and cav losses. Often times they will all get themselves killed.

Two, they are useless for defense, because with the wall buff an archer does more damage sooner then either unit.

Three, they are pretty useless for attack because this is a turn based game. People are talking about how cav and catas will ride right around the melee units and attack the archers. Well, thats the sort of strategy that only works against newbies and carebears.

Most people are going to have at least a couple cav and catas. Either left over from experimenting with them, or for the rainbow strategy, or for cav spamming ect. Because this game is turn based, 1 cav and cata on the enemy enemy's side will pin down your horse long enough for the enemy infantry/pike to engage them, completely destroying all of their famed archer killing potential, and turning them into hyper expensive and hard to replace arrow fodder.

Four, if the enemy has enough of a meat shield, your Cavs and Catas will charge into them instead of the archers, again turning them into hyper expensive and hard to replace arrow fodder.

Until Evony figures out basic tactical doctrine (I.E send in the cheep disposable troops to pin down the enemy, then ride in with the elite forces, not the other way around) high priced high speed units are a liability.