Your 15 a month doesn't entitle you to shit, it doesn't entitle me to shit and nor does it entitle Jim bob down the road shit, I may sound like an ass hole but its the truth. The whole reason for an MMO is 2 things:1. time and effort and 2. A whole lot of players grouping to do things. If this is to real for you then you may wish to go to the Chinese servers where you can pay by the hour.
1. Time and effort - If you log in once a week for 2 hours be it because you work a lot,Have a whole heap of other games to play or are one of those players ( Not saying you but just speaking in general ) who cries that there is little to no content to do, Than why do you deserve the same loot,rewards or "prestige" that say someone who logs in for 7 hours a day 5 days a week?
The answer is you don't!
2.Playing with lots of people -The whole point of an MMO is to group and meet new people while making friends to challenge content be it raiding,instances or even PvP if you don't want to group with other players for the raid equivalent gear to play the "fun spec" of your character why dont you play a single player game? like Warcraft 3 you still get the Warcraft "story" and can play how ever you want.
You may be asking, What the hell is the point of this post?!well that my friend is easy : No matter how much time you are able to play there are guilds all over the world with perfect raiding times to fit everyone.Hell i remember back in MoP there was a raiding guild who raided twice a week on 2-3 hours and i think they either killed Mythic/Heroic Garrosh or were very close to killing mythic/Heroic Garrosh which is impressive in it self. It all comes down to how much effort you want to put in, Want to raid with the "big boys" and get the best loot? Well get good, put in the time and effort and you too can have all the best gear and play the "fun spec". Want to put in no effort,log in with random people in LFR that you will never see again nor have to learn the fights, well be happy blizzard allows you to see the content with a raiding option that is aimed at people who are not very good/new to the game and people with very little time.