While 10 hours a week may not be enough time for endgame activities, it's enough to do other casual things. Endgame activities, contrary to popular belief, are far from the only things in game to do. You can do other small activities ranging from chocobo racing, chobobo raising, crafting, fields of valor, obtain and level an adventuring fellow, Moblin Maze Mongers, simply explore new areas, and much more. You could even try out roleplaying to see if it interests you seeing as roleplayers are in some cases casual players themselves with even less than 10 hours a week to play the game (see my sig for RPing details). If the game interests you, you'll find something to do in your short amount of time no matter what. You may not be able to obtain the greatest gear and whatnot with so little time but there are numerous other "accomplishments" one can achieve outside of just obtaining said gear.