I haven't really considered fumble damage yet. Since it only affects 1/5 of your attacks instead of all of them, and strength also indirectly increases the damage of your fumbled attacks (since the base is larger), I doubt it's a major factor. I have no idea how to measure the value of elemental procs, so I've been ignoring those too. Item requirements can be met with level rather than stats, but I guess that could potentially delay your damage by too much for it to be worthwhile (at least in the short term...at max level it'd be a non-factor, but I know it's silly to judge builds only by how they perform at level 100). I don't know what high-level requirements look like.
But in general, the way stat systems work is that the more damage you have, the more crit is worth relative to more damage, and the more crit you have, the more damage is worth relative to more crit. That's true in Torchlight as well. But your crit multiplier starts at a measly 50% while being hugely increased by strength, which massively skews the weighting in favor of the damage stat. Additionally, dexterity has straight-up diminishing returns (the amount of crit/dodge% gained from each point diminishes as the total goes up). And on top of THAT, Berserkers and Outlanders have better-than-base crit chances right off the bat, which gives strength even more of a head start. It's really no surprise that you'd want 3-4 strength for every one dexterity.
Dexterity as a compromise between offense and defense is pretty reasonable, but you still need a big strength pool to support it and dodge hits diminishing returns if you overcommit to dexterity, so you're still probably going to want to be favoring strength at least two to one.
(And for the record, I was the one arguing against dexterity in the aforementioned debate. This person was claiming that you should go pure dexterity and vitality in a build based on Glaive Throw because focus was a waste on top of the percentage-based bonuses you can find on items.)
EDIT: Another way of looking at this: 50 strength and 0 dexterity gives you a 25% damage boost. 0 strength and 50 dexterity gives you less than a 5% damage boost. Since strength is a rapidly-increasing percentage of your base damage and dexterity is a gradually-increasing percentage of your overall damage, it takes a very, very long time before the marginal benefit of strength has decreased enough for dexterity to start looking good by comparison.