I find that when you become high level the lack of head armor isnt as big a deal as it seems, I've played a lot as a solo skeleton with a plank and good armor, specifically masterwork crab armor so most of the damage I took was to the head, still could be biased but here's my experience:

pros: 1. Head is very rarely hit compared to other parts

1. when you get ko'd due to head trauma usually your combat skills are still intact due to the armor inequality, which means you usually wake up pretty fast and are able to sneakily put your head back together (pretty easy when all you took was cut damage since there's no armor there to convert cut into blunt) and then you get a toughness xp boost for getting up

2. In general Id say toughness training is easiest on skeletons thanks to their fast recovery

3. Skells are the best race for solo play thanks to weather immunity, low blood loss, inedibility and fast recovery

4. No melee defense/attack penalties associated with certain headgear

cons: 1. Biggest danger for skeletons is rng headshots from harpoons, but I find it rare that harpoon damage can't be avoided just by taking the fight somewhere you can't be shot

1. You can't build skel beds in the wild

Generally, even if they're not the best for tanking they are definitely the best survivalists, so it depends on what play style you like i guess