The spear you show actually has the biggest damage boosting prefix (inhuman/merciless/monstrous/sadistic), so it is definetely boosted. I agree though that you can have much higher damage with other boosts and better base weapon.
Charm is indeed less useful in the lategame because there are no enemies worth charming, but at that point the game is so easy its kinda poitless to compare if it takes one or one and a half turns to kill everything. It's quite useful throughout the longer part of the game. Charm deals damage btw, since enemies attack each other but its of course not cost effective in terms of pure dps.
In terms of dex, its up to you whether you level it for accuracy or not, but you have the same number of ability points as everyone, so if you put them elsewhere you get some other benefits. Or you can leave hard CC to the mage, who is being able to knock down everyone in a mile radius with a single spell and get the 100% accuracy.
Regarding STR, WW caps out at 19 STR, where it deals 180% weapon damage. Being a "spell" and thus not being able to benefit from stuff like guerilla and bully (but nevertheless having its damage reduced by armor, unlike most spells) and costing 6 AP, it hardly an ap efficient single target attack. It's a good aoe, although not nearly as good as top mage spells. Flurry is a better single target attack, but again, if you count in being unable to use guerilla and bully with it, it's actually not that much better than regular attacks. Let's say that Ram is not an impressive ability damage wise.
You are correct that dex classes don't have any good aoe (I've mentioned this earlier as well), but in terms of single target it's quite possible to build a rogue that will outdamage 2h. Then again, spells are better aoe than both in my experience.
So overall yeah, str classes are probably a bit more useful, having much better aoe and let's say comparable single target damage, but I wouldn't say there's a huge gap between the two and at certain points of the game dex chars are actually better, so both types of chars are playable and it depends on what you enjoy more.
