For me the issue is not whether "games are a healthy hobby", but whether F2P games are. I think they are not, or rather I should clarify: the kind of games usually called F2P or "freemium", which base their gameplay on grinding and which try to make you spend money to buy coins, which are powerups that essentially "speed up" the boring parts of the game are not a legitimate, healthy hobby. They are preying on people's addictive behavior while providing very little genuine value in return. They are what people like Jonathan Blow (of Braid fame) derides as Skinner Boxes and what Ian Bogost mocked with his game "Cow Clicker" (http://bogost.com/games/cow_clicker/).
I'm a Kongregate player and there are true gems in there, but most F2P games can be safely disregarded. If it has coins you can buy, or you can spend real money to bypass parts of the game, this is a huge red flag. (Another genre that I completely ignore is the overcrowded "Empire Building Strategy Game", which if you pay attention is always the exact same game with a different skin every time -- and most are F2P, while we're at it).