I once QQed like a lot of u are doing over being killed by cav but I tried cav before starting a thread like this one. Cav can dish out a good amount of damage (one hit kill sometimes) but if we're not patient/skilled we can get one shot killed too, it goes both directions. Also, we pay a lot for upkeep, a decent horse is 20k+ alone plus you add the price for a lance (heavy lance is 6k for example) and that's without shield and armor... in résumé it's expensive: you need to sacrifice armor to afford a good horse. If you tell me "oh you can take a palfrey or some low budget horse and still be OP" ... like not really! 2-3 arrows of Qaki with his kergit bow took my palfrey down and it was full health and no headshot! and he wasn't the only archer that annoyed me on my horse. Also, controlling your horse and stab at same time makes you pretty much "tunnel vision" on ur prey: you can't really see in front, in ur back or on ur other side, so you can now be easily back stabbed by another cav or somebody hiding near. For the "pike is not an offensive weapon", stick togeter, only one or 2 pikemen with a good situational awareness playing in a group with teamwork can easily protect you from horses AND can be really helpful in melee. I already did a dedicated pikeman once and I can tell u it's really effective with teamwork and I could easily one shot a horse and it's rider (stab from the front in the neck of the horse, it will kill the horse (if it's running fast enough) and kill the rider at the same time), you can also stop a horse by stabbing it on the side at an angle of 90 degree or less from it's front and poke it again and it will kill the horse for sure and than proceed in anal raping the cav while he's taking a nap on the floor. So many times I went around a corner to get one shotted by a (regular) crossbow in the chest cuz I had the speed bonus working against me. Same thing goes for archers, good archers killed me and other cavs a lot of times that way.
Oh and having more cavs on battle servers has increased the amount of dedicated pikeman, which gives a whole purpose to a class that did not existed pre-patch due to the fact that anyone could hide a pike in their poket and stab you in the face at last second. Also, it's not true about the cavs not going after another cav, it's much likely the contrary. Whenever I see an ennemy cav, he goes after me (or I go after him) and whenever we're a group of cavs in same team (not necessarly from same clan), we just stick togeter and gang on ennemy cavs too.
IMHO the class is alright cuz it's an expensive class and it's like a glass canon: do a lot of damage but risk getting killed really easily.
Edit: thx for taking the time to fully read my long text lol