The Impossibility of Balance
A lot of effort goes into balancing armies and units so nothing is overpowered (OP) or underpowered. "XY needs a nerf" is a the most common post title on PC gaming forums, and in the more competitive points-centric wargames. Points systems by nature can never be perfectly balanced (even the mirror opposite armies of Chess aren't balanced - what's with that white army always having the first move, eh?) so why do so many games focus on what is essentially a futile pursuit?
War is Asymmetry
Any good historical general would always prefer a guaranteed victory by creating a favourably unbalanced situation. "Get there fastest with
the mostest." And here we have wargames ignoring one of the key facets
In EvE Online, a spaceship MMO where losing your ship means losing the hours spent crafting it - most of the effort goes into ensuring the battle is unbalanced as possible. Players are more "careful" with their life when they can't simply respawn in 5 seconds and tend to set up asymmetrical fights in which they can lure an opponent into an unfavourable situation to be "ganked."
Asymmetry can't be stopped anyway....
In "balanced" points-based games, the asymetry is simply moved to a list building meta-game. I.e. to stack your army with as many "flavour of the month" units which have a game impact far more than their points value; or come up with a scheme to cheaply neutralise your opponents' best units. Despite both sides having a "balanced" 1000pt force, often it is evident who will win at the deployment phase before a dice is rolled in anger...
The aim of the game is asymmetry
Within even a supposedly balanced game, the aim is to make the game even more unbalanced and asymetrical as possible in your favour, as soon as possible. Knock out their units, maintain yours, angle for the best dice roll modifiers etc - that's how you win.
Balance is more fun!
Not necessarily. I'd say there can be more fun in having lots of choices (decision points) in how you manage your forces. For me, anyway, "not fun" is feeling you have no influence on the outcome and you might as well be playing Yahtzee with your expensive, carefully assembled miniatures.
Quite often I'll throw two armies on the table and offer the choice to my opponent, pointing out the one that is stronger. Quite often they will pick the weaker side themselves, and I find asymmetry tends to make games more convivial and less intense - i.e. no one gloats when they know their opponent gave them the superior force.
There are more than a few boardgames and PC games which has asymmetry as a key feature - be it a PC game against hordes of AI enemies, or all players vs a dungeonmaster. This thread was in fact inspired by my exploring co-operative wargames against "AI" controlled opponents.
Campaign games have a degree of asymmetry as sides lose forces or go into battle under strength - or "level up" at different rates. You can lose a battle with outnumbered forces but "win" strategically or at least force a "draw" which is favourable for the underdog. My experience with Frostgrave has shown limiting the turns can help stop the superior force from steadily and inevitably crushing their opponent by forcing them to take risks before time runs out.
Scenarios (historical or not) can have inbuilt asymmetry - many players enjoy the challenge of playing as the underdog. You can simply set victory conditions at different levels - or even set up the terrain/tactical situation to allow the weaker side a fighting chance. The two sides may turn up at the battle with vastly differing goals. That's where "secondary objectives" and "hidden objectives" like in Malifaux can add fun. Or perhaps give the weaker side better intelligence and initiative or superior battlefield position.
Whilst I'm not saying to abandon attempt to balance games nor points systems are evil (in fact I am in favour of points systems to "help" balance - without accepting them as a perfect solution) - I think asymmetrical battles should play a bigger part in the already overlooked areas of scenario/mission design. After all, how many historical battles were precisely balanced?
It's not an either/or situation.
Asymmetry (whether we acknowledge it or not) is a key factor of warfare both before (whether it is through meta gaming the points system) and during (as you attempt to quickly neutralize your opponent and gain battlefield superiority) the battle; so why not consider it in scenario and mission design in conjunction with "balanced" points systems?