MOBAs are easier to make yes, but to attract a player base, you need to be special, have flair, and a little luck. I think Turbine should have just made a new MMORPG as they're skilled at to play it safe. Can you really make a MOBA attractive when there's only like a dozen or two DC characters to select from, and you still have to unlock a majority of them? To me, it seems like Turbine is attacking the MOBA scene like it knows what it is doing, but they probably don't. I'd like to be kindly surprised as I'm a Turbine fan, but their mainstay is good quality MMORPGS
With Blizzard doubling down on WOW and cancelling their MMORPG, there's no MMORPGS on the horizon that I know about that could be any good. I wish Turbine would make Asheron's Call 3 and not even consider it being a WOW killer. Just go through the motions, make a successful and big MMORPG with modern graphics, and you're going to get a player base as Turbine.
I bet Turbine would be a great place to work at, but none of their projects seem interesting right now. If they have deep pockets, they should be making more games than just a single game.