(Btw, that "Flanderization", is that a real word ? 
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Only for those who use tvtropes or urbandictionary. (Also, it has nothing to do with Flandre, it describes when a character becomes one-dimensional by exaggerating one trait to the point of all others dropping by the wayside over time. See: Flanders from the Simpsons)
I disagree. Starting with a trope(s) and then building the character around it is backwards. It will create a flat, predictable and one-dimensional character, because their conceptual foundation is literally a stereotype.
Using what is supposed to be a tool for spotting template patterns in character traits and plot devices to create characters and plots is like starting with a stereotype and building a person around it. It might be easier but your character will read like a template; not a person.
I do agree that building from tropes or archetypes upwards tends to make a flat character with quirks tacked on for "depth", but I also think it's possible to portray a character that in the author's mind has depth using these devices in a detail-constrained medium. Take EoSD, for example. With only a few lines of dialogue for each new character, the most efficient way to present the audience with an understanding of what the character is (probably) like is to use tropes and the like. Sickly mage in a library? Probably stronger than her station would imply if not for her illness, spends almost all her time reading quietly, not particularly outgoing, likely doesn't take the initiative much. You could have the most well developed character in the world, but if you only have a paragraph to describe their personality, history, motivations or whatever in, it will probably end up feeling like a rush job. At the worst, the sheer number of adjectives thrown in at once could make it sound like an author favourite or mary sue.
In the best case, of course, after this initial portrayal other works would flesh out the characters, as was the case in PMiSS and the like.
