Maybe in your world, but in my world the guy with the greatsword gets one swing that is easy to predict and therefore easy to dodge before the guy with the dagger is slitting his throat.
I think my world is closer to reality than yours.
Um, okay? No, but okay.
Unarmored peasants preferred spears and polearms over kitchen knives for a reason. Tall guys with long arms have advantages over short guys with small arms, too. In every combat, up until the point you're basically wrestling with one another, you have the advantage if you can reach them and they can't reach you. If your weapon is shorter, you need the other guy to be unaware of you in order to make it work - or within their effective reach already.
Speed factors in 2e get it exactly wrong. Look, for instance, at spears vs. daggers. Spears are in no way, shape, or form slower than daggers. They are long, giving you a lever-type effect at the end, allowing you to move the point very quickly. Stabbing is a similar action in both cases. And yet, spears get the shaft (ha!) on speed factors.
Finally, look, I'm not one to claim that anything like SCA or Belegarth-style boffer-combat gives you any kind of real combat training or experience. It doesn't, and people who think it does are ridiculous. However, certain principles are rather universal to all fighting, real or fake. Reach is one of these.
This whole "dodging a clumsy blow" thing is a
fantasy - which, I might note, is
just dandy for D&D, hence my reluctance to include reaches and speed factors in D&D combat.
Reach is a very big consideration on any melee combat. Whether that's boxing or greatswords.
Also, optimal greatsword use is not necessarily in dramatic huge swings that are easy to predict, mm?
Yep, exactly. Heck, in medieval sword manuals, you'd sometimes do crazy stuff like grabbing your sword's blade and hitting someone with the pommel.
-O