The only argument I understand here speaking for uncovering game data to the players is (way too much text, sorry, I had to break it down a bit in speed-reading):
I can't play my <insert D&D class here>.
This is why (I as a player hope) it will never happen:
- • This is not D&D.
• Mages and Druids and such need high mental/spiritual attributes 
• This is not D&D.
• RP is about acting, but also about REacting.
Especially my last point in that list deserves some consideration. You must obviously be living in some sort of fantasy world in your head if you think that you can start playing the game as a Lvl18-Sorcerer just because your history is so fancy (in P&P the DM would probably tell you "Sorry, the other players in this party are having their characters start at Lvl1, so will you, so please revise your background history"). Although you know you will start out with the equipment equivalent of a beggar, and the skills worthy of a weakly child who can't even beat up magically-mutated flies.
--
Here, allow me to dissect my character Sian in a short study to display why this talk about knowing how to be "effective" in game is nonsense (keep in mind also that Sian is my very first character I played in Illarion, I had no idea about prerequisites in attributes in order to gain any abilities):
Concept & Background
Sian was a brigand and bandit who was supposed to follow in the footsteps of his older sister and father, both of whom were knights. His sister was killed in a skirmish though and he turned his back on this destiny, and became a brigand with some childhood friends, who robbed people in the forests. Eventually though, there was a setup of a "money transport" that was only a trap for the bandits, and Sian ended up killing his own father in the skirmish, only finding out immediately after the battle whom he killed. He escaped these "homegrounds", just wanting to get anywhere from there; just as far away as possible. This led him to a journey on a ship, which was wrecked in a violent storm at high seas in the month of Bragon, and he was washed ashore of the island as so many others.
[Gaming in Illarion begins]
Conscience weighs heavily on his shoulders (he's not the dumbest nor near-sighted to realize he's fully responsible for his own fate, and has nothing to blame on Gods or other things). Initial days on the island, he's still absolutely weakened from having almost drowned and went for days without food and drink; thus he can't even hold a blade straight before him. He begins working both as a digger for glassblowers, and eventually even takes up some occasional glass-blowing himself, although mind you, he is not a druid; he may have had some connection to the forests, but his allure to magicks had always been greater (he read the book of magic first). Regaining his security with blades in countless duels and operating as a linebacker for warriors and other fighters in defending the town, he eventually began to excel at his original and most devotedly followed trade: combat. Still though, he watched a coven of mages Athian had reinstated, and slowly picked up knowledge from them. He used to accompany Elminister in strides through the woods, in which he cut wood for the Knight, and the Knight in turn eventually gave him some items necessary to learn magic (yes, go figure, I made a CLEVER rogue, not a drooling idiot who would be incapable of learning magic due to some attributes—perhaps I originally had in mind he might be able to cast magic one day, but I left this completely in the blank and open; at any rate I didn't want a
dumb fighter). And in such, he came into control of ice magicks, the only type of the rune sorcery he feels affinity to.
Etc./find out in-game/good luck finding out the above in-game too
Note: As you can see in the concept, a single paragraph describes his history and what the character used to do, background-wise. Nothing more. Nothing fancy. Still though, I had a premise for how I'd basically play the character, with which I could distill even a little bit of humble prose around that single paragraph (if you search on the forums, you'll find that I used to write a bunch).
Premise
"
Sian fights against justice in order to end any injustice he can grasp."
A premise leads from point A to point B. (This is a technique of forming dramatic writing around the premise; and it is written of and detailed by the playwright Lajos Egri. I'd recommend his book "The Art of Dramatic Writing"). Getting to point B involves conflict, in the case of placing a premise over the character, I will automatically generate conflict, and thus RP, simply by starting from point A ("fights against justice") and knowing that I will slowly let him advance towards point B ("end any injustice he can grasp"); and mind you, still being fully aware that the transition ("in order to") will cover an indefinite, perhaps even infinite amount of time.
With some piece of mind and logic thinking, this Premise alone shows that I never had to depend on the character being a good fighter, or becoming a spellcaster one day; these things just evolved naturally in the RP.
In the case of Sian's premise, to fulfill it, I had to do no less than defend the honor of outcasts and criminals, stick with them, always try to secretly undermine Lyrenzia/the Town Guard/the Grey Rose, and operate with people who eventually formed Varshikar; with the single limitation that the character would try to do these things as peacefully as possible and try to prevent bloodshed where he could. This also all led to a wonderful synopsis of what Sian would excel at, aside from any skill or attribute ratings impaired by the game.
Character Synopsis
Sian is a cunning liar and trickster, and in his deepest core he is an escapist.
Final note: Keep in mind that the Character Synopsis and the Premise slowly became crystal-clear in the course of RPing, all I had to start out with was the initial paragraph in Concept & Background. The Synopsis and Premise are results of REacting to the game setting, environment, other characters, you name it.
'Nuff said.