Are you sure most RPGs are turn based because the battle system is complex enough to make it mandatory, or just out of preference? Something like X-Com, yeah, but I don't think the games he had in mind are really quite like that. That said, there's no objectively superior option, so developers will keep making both turn based and action games as long as people are willing to pay for them, and there's nothing wrong with that
Oh, absolutely. Where both are feasible, why should it not come down to developer/customer preference. On the one hand, I love the spectacle of the action combat of Star Ocean, Dragon's Dogma, Fallout, Dragon Age or Ys, and on the other I like the sense in Etrian Odyssey or Grimrock or DQ or SMT that every move counts. Also it's tied into the roots of RPGs as tabletop games (and previously strategy wargames), I suppose, but that's not a bad thing, there are plenty of them that translate very well into computer games as not every game needs to be an adrenalin rush just because they can be.
What I don't agree with is the sentiment that, because consoles can run awesome action games, it makes anything that requires and encourages a few moments thought redundant. I like to have a bit of variety, and sometimes I'd rather play a more sedate game, with more in common with the tabletop style, each action carefully chosen over as much time as I like with a nice cup of tea, than be charging around at a rate of knots whacking monsters. Sometimes I'd rather do exactly the opposite!
Perhaps it's just that I find turn-based particularly suited to the more difficult dungeon crawlers due to the resource management being a large part of it.
Monster Hunter is something else entirely, for me I love the action-based combat there, as the strategy element is evident in the preparation. You can spend as long as you like tailoring exactly the right loadout, abilities, consumables and traps, increasing your chance of success, and you can only carry so much. Often there is a break in between scraps with the beast to sharpen your weapon, heal, regroup and discuss what bits of it to target next. In that way I think it contains enough variety to cover everything I want, the buzz in the tavern as the group musters, the tempo of the hunt is high as everyone starts off searching for and then racing towards the beast, followed by brief breaks as it goes to ground or leaves the area, the high of the win, and the obligatory moaning back in the tavern about how the game knows what you want from the carve but is denying you your new hat! It makes each session feel nicely paced. I must have put 400 hours into the series by now.
/edit: on reflection this is a long-winded way of saying 'why can't we have both?