Agree with Joker, bumpslash is unrealistic easymode. 1h cav should support teammates or attack unaware enemies and not bump everyone and kill. For frontal assaults there is lance cavalry. Different roles on the battlefield make teamwork important and the mod deeper.
Okay, I will analyse who you are referring to with that "everybody" there.
Polearms ? Impossible, the horse is stopped or killed and/or the rider is killed.
2h ? Impossible 2h thrust are 2 to 3 times longer than any attack of a 1h on a horse. The rider dies.
Archers ? Yes but only if the 1h cav manages to come up close without loosing his horse or being killed by an arrow. The horse will atleast take an arrow, probably in the horse's head if the archer is aware of him.
Throwers ? Nope. You or your horse dies before you can come close.
Crossbowmen ? Only if they haven't seen you before they shot. If they see you and they have a bolt loaded, you are better not trying anything if you want to keep your horse (and usually yourself too) alive.
Other cav ? No bumping on other cav, einstein.
Finally, we have shielders. As they still often do the mistake of turtling up against a 1h cav, they are the only real "aware and easy kills" of 1h cav. If they react correctly, however, the 1h cav might still kill them but at the expense of a big slash in his horse.
Also, about this lance outreaching 2h nonsense, I did it myself with a DGS against many cav. It's just piss easy. On the other hand, outreaching a DGS as lancer requires perfect timing and that the 2h doesn't time his thrust right.
Anyway, even if it was true that lances outreach greatswords, why bother when you can jump on the side and slash them, dodge backwards, block or even chamber the lance (the easiest chamberblocks IMO).