This is the version 2.0 on my view into the f2p world. So you got it, is my view not one of those statistics on the market.
Few years later, and supposedly wiser :) I still think that the main quality of a f2p game is: you can play for free. So then what is the main defect?
As playing I noticed that the f2p system involves a never-ending play time that keeps the game going ... and going ... and you got the picture. This works very well with some genre like building strategies and sims and not that well with others like RPG.
You see generally speaking these games are based on patterns. The human brain is built to make patterns, this is the way we learn things. The pattern prints into our brain the instructions for doing something and repeating the pattern over and over helps us mastering that something. Repetitio mater studiorum est - the repetition is the mother of learning.
Now back to the RPG you see I played these games for a long time. I got used with the great stories and the large open worlds of the payed ones. Yes am gonna say Gothic again. Why? Because it was the first "big" RPG I played and one of the things I enjoyed the most was the vast world to explore. I even got lost in the first day before getting a map. You could very well finish the game without covering all the caves, rocks and plains of the world. And there was the great rewarding finale - and I want that ending like saving the world, the princess, the whatever. Very few f2p RPG are giving that kind of world and that kind of feeling. Especially in the mobile ones you have a small world with up to 10 map locations which you will learn quickly as being fixed and not changing in layout. Just a bit of different background and monsters. I remember some time ago I told to Jim Squires (EIO on Gamezebo site) that his guide for some game fits to many other games generally. Why? because these games are having the same structure: up mentioned static map levels with 3 difficulty modes, resources dungeons, arena, boss fights, guilds, chat, daily/weekly quests/rewards and achievements. With minor variations. all of them are registering an ascendant curve in the first days from launch. It's the novelty and the promise of a hopefully good game with a constant income of new players. The exciting phase. Then slowly but surely while the game "duties" are becoming a daily routine the income settles down. Less new players are registered and veteran players are starting to abandon the game. Because as much as it likes the pattern at some point the brain becomes bored with it. You know that guy Heston Blumenthal with his food chemistry? Am not fond of him but he has some points. He wondered about taste. Why the chewing gum that has millions of micro-particles of aroma loses it's taste after a while? In reality the taste/aroma doesn't disappear but the brain becomes bored of keep registering the same info and blocks the communication channel. Thus you don't feel the aroma anymore.
Same thing happens with the players, some of them are becoming addictive and the routine gets printed in their daily schedule. But others, and after a while many of them, are getting bored and abandons. And this is the main defect of f2p: no mater how well the game starts it will enter, sooner or later, into the repetitive up to boredom phase. Many games especially the reasonable good ones manages to keep a constant in between newcomers and abandons but, regardless of how you look, this linear constant for me is the flat line. Is not an accountant or mathematical flat line is that cardio monitor flat line that means "game over".