Take my info with a grain of salt but the reason dex mods and padded/lights/wilds bases are recommended are because A) most of the late game classes are only able to use weapons that scale better with dex (dagger, staff, spear), B ) padded has higher defense values (slightly worse magic defense with twice as high physical defense) and finally C) the only charms that the Headhunter class can use are Lightning and Wild Heal. Because of the way MQ works you have to do many more runs as characters which scale better with dex and have armor/charm restrictions to robes/Light/wilds so dex mods with those bases are worth much more because of usability factors.
Wouldn't normally chime in as it's been many years since I've played and I have no fg estimate, but figured I'd give my two cents and if I'm corrected I'd learn something.
spear is nothing to do with it. the main point being dagger and axe cover all the melee classes and probably upwards of 60 sets exist, so thats 60 sets of dex gear needed. I believe there are 2 spear sets "in use" with about 2 sets not really being used seeing they have better daggers.
If you use strength gear, you'll still get stuck on monk whom will want dex gear. "if" this one class could use a strength weapon then things would be more balanced. However it is still a somewhat viable option of going swords + staffs + axes which also covers all the classes and means you can buy in HH usable strength items instead which are cheaper.
A few people do clubs + daggers and just borrow the axes if they ever reach HH which again allows str hh gear
Rest of it is correct.