Actually Phoenix is wrong.
One of a Staff's Attributes that enchanting enhances IS magic attack, at a rate of 40 per enchant level (+400 at level 10). Enchanting ALSO enhances staffs by 10 physical attack, so they double as a viable melee weapon.
As for the purposes:
Heals are 66% of Magic attack + the heal skill's base.
Poison Skill's Base damage is approximately 22% of Magic attack Plus skill Base.
Dark Skills range from 20-40% of Magic attack plus skill base.
Magic attack also adds to poison ticks:
1 poison per 50 magic attack up to 400 magic attack;
1.5 poison per 50 magic up to 800 magic attack;
2 poison per 50 801+ magic attack.
In other words; yes your staff needs enchanted, or you will not be a potent damage dealer, healer.
(Staff enchant can easily be credited with 30% of a SM's total damage potential).
Personally I think the wiki is lacking in regards to information at all on enchanting atm. It says nothing in regards to rates, power stones, protection scrolls, cost to enchant, possibility of enchanting failer costs. It's just vague flavor text at this time.
Word of advice to god:
While rares are pretty inexpensive to enchant, Heroics have a fee that start at 10,000 gold and raise 1000 a level; Heroics have a fee that starts at 30,000 and raises 5000 a level; Legendaries have a fee that starts at 100,000 per try, and I haven't personally experimented with them to see the increment in increases (I wouldn't doubt 10,000 per level)
I don't think anyone knows quite how they work now. In CB, they had % increases to chance of success that increased 8% per level of stone. Now, they read as follows:
Power Stone 1.1:
Helps Uncommon (Green or lower) up to 4
Power Stone 1.2:
Helps Uncommon (Green) up to 4 with greater chance
Power Stone 2.1:
Helps Rare (Blue) up to 6
Blue up to 6 greater chances
Up to Epic, 9
Up to Heroic, 12
Up to Heroic, 14
And I'm guessing 6.1/2 is Up to Legendary, to 15.
(In other words, if the new flavor text is true, that means be careful what stones you use, although it's pretty easy to get - just on gold alone).