Part of the reason I wanted to make that explicit was to start explicitly separating things 'any wizard can do' from hings that 'only some wizards can do'.
For example, the folding sunlight trick that harry does in Grave Peril. Is this something (sorta) exceptional that Harry does, or is it something every wizard can do? Is just saying "my character is happy" enough justification to let my PC this? What about some other catch bypassing trick? If sunlight is (relatively) easy to store?
As the books and samples of play expand, 'stuff wizards can do' will get more and more stuff added to it.
As a sample, we have Harry's belt buckle in, erm, Fool Moon?, LTWs shapechanging, and )forget his name) super speed in Ghost Story. Even Harry moving himself around with force magic is not something really covered by the rules.
Another example is the knowledge of the Ways that Harry gets in Changes. Is this pretty much something that every wizard can do? Hop around the world, more or less safely, and pretty much at will? Or does this require, say, the world walker power? And if it does, what portion of it do wizards get 'for free'?
When I first read the rules, my impression was this:
Harry can move himself around with evocation, thus, evocation can replace (some) skill uses, this is reenforced with the rules about veils, which replace stealth. As I didn't really want spirit to be the best element, I thought that the other elements should probably have similar skill replacement trappings too. And since force jumping and veils appear to be 'free' extras of spirit magic, the skill replacement trappings of other elements should be free too.
Wizards and flight:
Harry mentions some attempts to fly on a broomstick (or something like that), indicating that he didn't really have any trouble getting himself into the air, but it was the control and attention required not to drop himself back onto the ground that was the problem. Of course, Harry was a teenager at the time, and even in his adulthood, his control (when compared to other wizards, at least) is nothing special.
So, being able to fly around is something that other wizards are perfectly 'capable' of doing, but just like, say, tightrope walking, is something 'everyone' can do, most people don't. If you want your wizard to be able to fly around, you should probably take the wings power, to represent your time spent actually practicing/learning how to do it well.
Now, no one ever seems to have objected to the second interpretation, but look how bad an idea the first one is. So, while I want to 'allow' the first interpretation, I wanted to explicitly make it be something that not every wizard can do. How? by making ti cost extra refresh, to represent the practice/concentration/aptitude, etc.
