A la carte games like DDO and LOTRO you can buy the current entire game for probably around $150 if you want. That's "only" 10 months of $15 a month. You can get pretty far just putting $25 or $50 into these games. You can look up reviews for each area of land and see if it's worth it to you to pay $6 to have access to the quests in land area X, for instance. If you don't plan on questing there because people say the quests there suck anyway, no reason to buy that land area, and no reason to pay $15 a month to have access to it.F2P MMO's are hardly "free" or "cheap". They end up costing far more than subscription based MMO's by the time you purchase all the content.
In LOTRO, you can access most every land and get xp for killing mobs. You just can't do quests there unless you buy that area. Seems like a pretty fair deal.
In DDO, since the whole game is instanced, it gives the developers more incentive to make good instances (or good land areas in LOTRO) since otherwise word will get out the instance sucks, and then no one will buy it. When paying $15 a month, they already have your money.
I guess I don't play enough "pay to win" MMOs to see what other people see. Yeah, some of them, particularly the Asian grindfest PVP ones may be like that, but, for various of them, the only things I can think of that make a difference with money is buying more character slots, more auction house slots, more bank slots, and maybe a faster mount. I guess it might be considered an unfair advantage if you can do things like buy a resurrection at the spot where you died, but that's a PVE thing. Most pay-to-win complaints are for PVP.
As far as I'm concerned, if someone else wants to subsidize my free games by paying real money to change the color of their armor or buying a cool-looking mount or whatever, they can be my guest.
Personally, I probably wouldn't play any MMOs anymore if they were $15 a month. It's not like $15 a month is going to break anybody, but I simply don't see the value in them at that price -- at least for the amount of time I play them. Though the subscription models actually benefit my playstyle since usually when I play an MMO I put it off until I can set aside a block of time, and then I play it hardcore during that time.
Due to the free MMOs now, it can help make gameplaying more efficient and a little less of a waste of time since you can keep switching between them and only play them while you have rest XP to level up faster. You're not paying a monthly fee for them, so you can afford to wait.
As for Elder Scrolls having a monthly fee, it makes for a good cashgrab for a while, but I'd be surprised if it lasts more than six or so months. That's probably the smart thing to do on new and popular launches -- tack a monthly fee on it, and then if (when) the population starts to dwindle, change it to F2P.