ARPGs are dime a dozen, even if this one comes with some extra gimmicks, large-scale RTSs are pretty much extinct.
I think you're getting your wording mixed up there, decent diablo-clones aren't dime-a-dozen, in fact before Torchlight they were just as dead as the large-scale RTS, and even since then the only notable titles have been Diablo 3 and Torchlight 2. What they are however is incredibly same-y, which is what GPG is trying to tackle here, it's not a gimmick, it's half of the experience and looks really interesting to me.
Also Chris already stated if they wanted to make a large scale RTS (specifically K&C) it would cost a hell of a lot more than what PA was asking for or even ended up with and with Uber already beating them to the punch, it would've been far greater a risk to take than what Wildman has been. He also stated he's interested in seeing if they'll be able to stay in budget with the scale they're going for, but some have already drawn the link that he may have been under the assumption they were including a campaign, which they aren't, or making specific maps instead of having procedurally generated planets, which they aren't, so hopefully they'll make it.