When I write game rules, I write them with an audience in mind. I didn't set out with this audience in mind, so much as evolve into writing for this audience.
The gamer or gamers I write for:
Actually game. Pretty simple. I write for actual play. I assume it's going to get used, or at least tried out before being discarded if it's not what the reader wants from gaming. So it's all got to work, and that takes priority over anything else.
Is part of a cooperative group. This is not to say no PvP, but rather, if PvP is there the players are onboard with it. The group is friendly, and playing together for enjoyment, and is willing to cooperate to make that happen.
Has a strong GM. My assumption is that the group has a strong GM. Not a dictator, not a pushover. The GM (and the other players) make decisions about play and stick with them. The rules provide sufficient cases for the GM to make decisions, but don't need to cover everything. I assume a strong Rule Zero approach.
Pushes the wording a little bit. Not rules-lawyering, per se, but rather wants to get the most benefit allowed under the rules and get the wording and spirit correct. A group that wants cases spelled out so they don't have to waste time figuring out what I was trying to do with a rule. But not a group that needs those words to settle an actual argument or as levers to use against one another.
Not too serious. I expect the person reading wants to enjoy reading game books. There will be jokes, Strongbad references, and implications of smile-inducing gaming fun. Whenever possible I want punchy writing that makes you sit up and want to game right now. Or, get ideas for gaming later.
That reflects my group to a great extent. My friends are willing to argue rules wordings with me or ask about the extended implications of them - but during play the GM's word is still law. Everyone is attempting to have the same kind of fun (or overlap sufficiently that it isn't an issue.) No one is too serious, even if the silliness is more deadly than funny. Everyone actually games, and prefers clarity of rules over good prose.
I know not all groups are like this, and I try to make allowances. But it's hard (maybe impossible) to write airtight RPG rules that prevent arguments and allow people to play with uncooperative disruptive players or who need the rules to do the GMing for them. But in general, when you read my rules, if you see how well they'd mesh with the above . . . it's on purpose. My audience is the friendly group ceding authority to the GM and placing the game over the rules, but using the rules as the foundational underpinning for the game.