I had the same reaction as you about subscription fees initially. So I purchased Guild Wars (GW) as my first MMO. Was a ton of fun for a few years and I bought all their expansions. Incidentally, it's also the game where my comic storyline developed from Role Playing in Guild Wars (and it took me a long absence of 2 years from my guild -was dating my now husband and all so it's not a bad thing- and just decided to go back again and reconnect with my GW friends once I settled down, resumed our storyline then realized we got something good going on went back to drawing - a hobby I abandoned for 7 years - and decided to make a comic. Just wish I started it sooner lol)
Anyhow, I mentioned that 2 year hiatus from Guild Wars when I met my husband. He's played World of Warcraft (WoW) and we had a deal that he'd try GW and I'd try WoW. Took me awhile to take in the concept of a subscription based MMO, but now I realized that it is actually a good deal , depending on your lifestyle/situation. Not as good of a deal as Guild Wars where you just buy it once and it's free but content and feature-wise, WoW beats Guild Wars hands down. Despite that, I don't consider myself to be a WoW fangirl, I've just tried so many MMOs and still go back to WoW so it's a long process for me to come into terms to that >_>
We've tried many subscription-based MMOs (Warhammer, Aion, Age of Conan, City of Heroes/Villains, That other superhero MMO that I can't remember, recently tried Rift and unsubbed to that as well) and nothing gives you your money's worth aside from WoW at this point. They put in content, great support, a lot of things to do in game, good gameplay mechanics, add-ons, and so on (I used to hate WoW because I was a GW fangirl lol). My PS3 became a blu ray player for the most part because WoW kept me occupied in terms of my gaming hobby. So that also saved me money because I wasn't buying the latest PS3 games for USD60 that I'll probably play for less than a month considering how much time I normally spend gaming. (note: I said latest PS3 games because if I didn't play MMOs and just played console games, I will be up to date in the PS3 games and thus will have to buy recently released games at a regular basis)
$15 a month is not a lot as me and my husband discovered when we both unsubbed to WoW at some point. We found ourselves being bored in the weekends so what we did was go out. We spend at least $100+ a weekend on food and whatever leisurely thing we decide to do and then feel like crap afterwards. I am not saying it's bad to go out and all but it gets old and expensive if you do it every weekend.
Subscription based MMOs is cheap entertainment overall when you just want to kick back and relax on a weeknight after a long day at work or a lazy weekend. Like everything, MMOs should be played in moderation.
Of course there are other productive things you can do like drawing or learn to play a musical instrument instead of gaming on your free time.
In fact, my husband unsubbed to WoW recently so he can work on his novel. I am renewing my subscription because a couple of my friends from Guild Wars are playing WoW with me on weekend nights when I am not busy. I don't game as much as I used to (I was in a hardcore raiding guild at some point in WoW)
On the other hand, I never liked the concept of pay to get extra features for an MMO. I tend to be competitive and I want a fair playing ground when I am gaming - where everyone has the opportunity to maximize their toons depending on their strategy/builds and the time/effort that they put in.
I hate being forced to buy something from a game I am already playing/purchased if I want my toon to be 'awesome'. It kills the gaming experience. It's like watching a movie and then getting interrupted having to Insert Coin if you want to see the ending. It breaks the momentum. I just want to pay and forget and get everything the game has to offer.