Quite the contrary, I could see it apply to these weapons, too!
My understanding of the Concentration mechanic is that it is similar to 4e's "sustain" keyword, but doesn't take an action, and if the user takes damage, the effect might end. You can't use two things that need Concentration at the same time, either. I don't have the 5e docs in front of me and it's been a while since I last peeked at them, so I don't know if this reflects the current RAW or not.
So, say,
Haste. Cast it and as long as you keep Concentration, your ally is hasted, but if you take damage, the spell might falter (I don't know if there's any check involved to mitigate the falter, but for the sake of a thought experiment, lets go with "no," and say it just ends the spell). Can't use
Haste on two people at once.
Anything you need space to use -- anything someone getting up in your face and beating you about the head and shoulders might disrupt -- might use a mechanic something like this:
[COLOR=#FFA07Z]Concentration
Certain weapons and spells take concentration to use, and are more difficult to use if you are under attack and taking damage. If you have taken damage since your last turn, you cannot take actions that require concentration. You can only use one action that requires concentration on your turn. [/COLOR]
That's not meant to be a final rule or anything, just a starting point that accomplishes the goal in a simple way (I'm already imagining CON checks to do it anyway). And it's more thought experiment than serious suggestion. But I kind of like the cut of that jib.
You want to use a lance or a longspear? Or a whip? You're going to need time. Balance. Bracing.
Aiming. It's not like a sword or an axe that you can just swing and hack with, these are weapons of precision. That's why you get the guy with the shield in front of you, or ride up fast on a horse, or strike from a distance -- if something disrupts your momentum, you're not going to be able to strike with it.
Heck, that's a flexible enough mechanic to apply to a host of things. A rogue ability a la sneak attack ("Ignore me, and I'll stab ye in the kidneys!") or Hide In Plain Sight ("You take your eyes of that halfling for
one second....!"). Most forms of winged flight. Magic item use. Wizard spellcasting, but maybe not Sorcerer spellcasting (really gets at the distinction of cautious, academic magic vs. instinctive, natural magic!).
At the very least, having a unified mechanic for this pursues the "elegance" that Mearls & Co. are supposedly enshrining as The Real Goal, in that it eliminates rules, solves a problem on multiple fronts, and reflects how you'd expect the world to work. It's also a lot easier to look up and remember one rule than it is to remember 2-3 sub-rules that all ultimately kind of do the same thing (that is, stop people from taking actions that require some precision when you're in the midst of a drawn-out melee).