It's important to understand that the hundred coders in a company will be implementing high-level designs, not making them. In design terms, you might get given a task like "design the graphic format to be used for all art assets" but you won't be given the task "design a way to encourage users to interact in groups of five to ten people". Or indeed be asked to design a solution to prettymuch any question from my list of basic MMORPG questions.
Game designers get to decide that stuff.
HOWEVER... don't think that being a game designer is all wonderful pie-in-the-sky imagineering, either. Most of it is research, math, data-mining, crunching numbers, and grunt work, and that work will be massively under-appreciated by almost everyone in the company. The advantage of this is that it's entirely possible your bosses will not know if you suck at it, because nobody knows what game designers really do.
An example I always give of why I could not be a game designer is that I had the joy of working with a good one: a guy called Ben Jans. He worked for Lolapps as a game designer on a game called Ravenwood Fair. Notice how at that link, you don't see Ben Jans listed there: you see John Romero, Brenda Brathwaite and Dr Cat, all those three designers deservedly being massive heavyweights in the industry.
So, the way I heard the story, about thirdhand because Ben is too humble, is that shortly after Ben applyied to LolApps for the job, the company director went to the hiring manager and said "why are you hiring game designers? Why can't you just get the coders to design it?"
The hiring manager handed Ben's application to the Director, who read it, nodded, and walked out, never to ask that question again.
Ben got his acceptance letter the next day.
What was in that application? Design notes for two questlines for the game. Not just a high-level overview, but extremely low-level: character names, lines of dialog with perfect tone for the game (including hundreds of carefully-researched references to the lore of the game, and countless gamer in-jokes), carefully balanced quest rewards (in a Farmville style game where every single action gives some level of reward), carefully balanced task costs, and far more, and summing it all up with a list of all required assets for each quest (sounds and graphics for the characters and their environments; each questline using all existing features of the engine, but requiring one small extra piece of programming just to show that he understood the cost of doing things that the engine did not already do).
In my vague memory, I think one quest was "the dragons visit the player's island", starting with vague rumors that the dragons were coming, culminating in meeting a dragon and getting to hatch dragon eggs... I completely forget what the other is.
Both were exciting, engaging, and novel, taking the game in slightly new directions without violating either the lore or tone of the games, like the very best DLCs you see for games nowadays.
Now, what made me realize that I could never be a game designer is that in order to do this job, he would have to come up with a new questline, in that level of detail, at that level of novelty, every single week. I'm not sure I'd run out of ideas first, or would get bored to tears by the minutiae first.
Just like everyone has one novel in them, so every programmer has one or two good game ideas they'd love to try making someday. Some do make them. Some of those ideas do actually turn out to be both good and successful. But almost all are one-shot wonders.
Most people are scared to tell others their One Idea. Scared it might get stolen. True creatives have so many ideas, they don't care - they just shout their ideas from the rooftops and hope one of them takes root. Like the rantings of the madman in Sandman's Calliope made me realize that Niel Gaiman must have an infinite supply of ideas, so working with Ben Jans made me realize what you need to be a game designer.
A game designer needs to have amazing patience and attention to detail, yes: but infinite ideas.
