Actually, people tend to be pretty lousy at making those kinds of distinctions, and in fact they try to only assimilate as much data as they need to get by.
This may be true for you, but whether it is a generalisation that can be validly applied to the population at large is another matter. The most obvious interpretation of "fly Dex mod squares" is just that: you fly for Dex mod squares. At the end of that, you fall, if you're not on the ground. This is without looking at anything else in the books, whether it's flying rules, falling rules, or whatnot.
"You can move an additional square."
"You can move an additional square when you take a move action."
A lot of folks would intuitively connect movement with move actions (for reasons that are self-evident, even they're not always accurate), and thus would think the former sentence functionally identical to the latter.
Then these folks have not been playing 4E, or at least have not been playing 4E for 16 levels.
"You can move an additional square as a shift"
"You can move an additional square with a move action"
"You can move an additional square when you take a move action"
"You can move an additional square as a free action"
"You can move an additional square as an interrupt"
are all rather different things, and this kind of variety in action cost is commonplace in 4E. The exact action cost is not something that you take for granted if you have any experience at all with the game.
You think the difference is that obvious? You have that much faith? By all means then, sit back for a few months and watch how many people think Dominant Winds amounts to all-day flying.
I don't know why you're so worried about the population at large. Their games don't impact you, and you have no say in how their games work. The nice thing about p&p as opposed to WoW is that everything is instanced, even the ruleset. That said, if you want to talk about the population at large, two results will probably occur:
- Ppl will think Dominant Flying allows flying, and they will adjust their encounters and adventures to match.
- Ppl will think Dominant Flying doesn't allow flying, and will rule it so in their game.
Both of these results can coexist with each other in the general population. There is no need for a single ruling to apply to the entire population, so long as each group is consistent in how they treat it individually.