Monthly fees don't guarantee a better or more balanced game, and F2P doesn't guarantee that everything worthwhile will be tied to microtransactions.
The problem is that this will launch with a subscription, and inevitably end up as F2P, at which point they'll start shoehorning methods of monetization in where they weren't originally planned. It'll end up being a hodge-podge of design where there are some good elements which have been ruined by the tacked on microtransactions (see: SWTOR).
If they just rolled it out as a F2P game in the first place I'd be more confident that they'd be able to design around it properly. LoL, PoE, GW2 (not exactly F2P but the principle applies) are all examples of how F2P can work just fine - but they're all cases where that was part of the original design.
edit: I'm sure the devs are already thinking about F2P, but I still think the initial subscription-based launch will result in design decisions that need to be hacked away it in order to introduce a microtransaction model, even if there is some planning involved.