"It's the mindset of the developers. As posted above, game patches and design decisions by the developers of F2P games are driven by a financial bottom line, with no concern for the playability of the game in terms of whether its fun to play or not."

You mean long level grinds and quests designed to have your character traverse the world several times over to complete? Reputations, feats, deeds, achievement systems, daily quests - the developers of subscription MMOs are just as conscious of their revenue model and design their games around it.