Reading through it..
"As we went through each Demigod, we came up with ideas that would make that Demigod play more uniquely. Examples included (depending on the Demigod in question), sacrificing speed for toughness, increasing money received from mines, decreasing cool down times on spells, increasing XP gained from killing creeps, increasing damage done to structures, increases toughness of nearby minions, and so on.
When we put together our first list, we quickly realized that just from the skills, you could make one Rook play quite differently from another rook and that was before we even started messing with items and equipment."
This sounds okay, on paper. But in practice, it'll be the term i've liked to use a lot that the balance will be "cracked".
With skills so simple, anyone who knows how to type numbers, *'s, +'s, /'s, and ()'s into google and copy the numbers into a .txt file can pretty easily calculate what skills are the best.
It's like in Diablo2. The skills have neat effects and function and all (I loveeee frozen orb! Going out. spinning around shooting out ice circles in a circle around it!) but.. everyone knows what the best combinations of skills and equip in that game is. It's very simple math.
In DotA theres a certain skill you get first, item you get first, and recipe you get first for each character.
You look at Guild Wars though, and a group of people can have completely different opinions on whether a skill is good or not, whether a build is good or not, whether a combination of builds together is good or not, and they can argue with each other about it endlessly and never agree. The skills have so much depth, there are so many factors that change how they perform, they are different in some situations instead of others, and what your allies are using makes a huge difference on whether your build is good or not.
GW has like 900 skills, but you can only use 8 of them, so it's not like it has all this deep balancing justbecause of the high level of skills. It's because the skills work more like the abilities in a card game like Magic:The Gathering more than they work like in a traditional RPG.
Just because you ALLOW people to play differently, and give them different options, doesn't mean they WILL.
I think asking the question "What sort of skills can we put on this Demigod" isn't as important as the question of how to get people to actually use the different variaty of skills and not all use the same ones.