And WiiU is the younger system. Good comparison.

It has been mentioned, actually, but it's not necessarily the case. It isn't as simple as, "This system is more powerful, therefore this system is much more expensive to develop for." If you spend more time trying to squeeze your game onto a lower spec system, then it can actually be more expensive than developing for a system with higher specs.

If they're creating the assets in HD (to be used later in MH4U for Wii U or something) and then scaling them down, I don't know why it would be significantly cheaper to develop on the 3DS. Or any cheaper, really.

Of course there are exceptions, but I think you're really grasping at straws here. A more powerful system doesn't equal higher dev-costs by default; that depends on the type of game -obviously-. Tetris on Vita would be cheap, and a 3DS GTA would be far more expensive, for example, yes.

Fact remains, a ground-up, full-fledged, AAA, fully-realized MH title the likes of MH4 on Vita would easily have been much more costly to develop than a ground-up 3DS version. One can always come up with 'what ifs', exceptions and best/worst-case scenarios, but in this case that just doesn't fly, no matter how it's spinned.

but to say it would do 3ds like numbers is massively hypothetical and also pretty unlikely even if the installed base doubled which again would still be largely guesswork.

What data? And why would the Vita need to be another PSP for Monster Hunter to keep being Monster Hunter? I can see why it would be insane for Capcom to move the series to the Xbox (in Japan, anyway, because I think the 360 would have been well positioned to finally make MonHun accepted in the west) but simply releasing the franchise on the Vita as everyone initially expected would seem like a very low risk move because the obstacles to adoption for the Xbox and the Vita aren't the same.

What even are the obstacles for the Vita? Price? Sure, price is always an obstacle for anything. Every price drop is met by some sort of bounce. It can't hurt to move more software, either, but the more price sensitive a customer is, the less likely he is to buy his games new anyway. Form factor? I doubt it. It's essentially a PSP with a second stick and no crappy UMDs. I think the 3G version may be a whopping 10g heavier than the PSP-3000. Lack of compelling software? Most definitely. I think this is the major one. Monster Hunter wouldn't single handedly solve that problem nor would it single handedly make the Vita into a PSP, of course. But I don't think it has to. The Vita doesn't need to sell exactly 1:1 with the PSP for franchises to perform as well on it, surely. It only has to be acceptable to the franchise's audience.

I guess nothing is ever guaranteed. There's no guarantee that many of the millions of people who just bought GTA5 in droves won't turn up their noses at GTA6 whenever it turns up on the PS4/Xbone. But I have a good idea that they won't. It is a reliable system selling franchise that has been extremely well handled such that its drawing power remains intact, and the latest entry is being extremely well received - and not just from "journalists" of questionable integrity. While Capcom may be getting a little happy with the Super Turbo Arcade Edition EX rereleases and little social/mobile/puzzle game spinoffs lately, the same can actually be said about Monster Hunter.

But anyway, I don't assume it would have pushed out exactly the same numbers on the Vita at all. I just have the feeling it would have sold roughly the same, perhaps marginally less but definitely in the ballpark. That's not to say that Capcom made a bad move by any means. If they are adamant about getting the series to catch on in the west without moving it to home consoles, the 3DS is the only chance of that and Nintendo is certainly more of a partner for them than Sony has been.

Once again,  Vita sales pale in comparison to pre-monster hunter PSP sales.   That's a gurantee of customer loss.

Afterall a number of Monsterhunter owners are likely those who bought PSP's early and as you put it... "put them away" right?

They're going to make the same mistake for one franchise?  Here's another thing I think your missing.   Most people who owned a PSP, likely owned a DS.   Look at the sales numbers vs the population of Japan.   Why?  Well Playstation WAS on top of the world when the PSP came out... like you said.    It isn't anymore... (Well not for a few months) and after seeing what a dissapointment the PSP was to most people... why would they own both again?   (Me I liked the PSP, but this is the assumption you were going with.)

You are right that it's essentially the PSP.... and that's what the obstacle is.  It's the PSP without the advantages the PSP started with, and the negative feelings the PSP generally provided.  Along with less compelling software... even with Monster Hunter it would of had less projects focused on it then the PSP did.

PSP sales don't have to be 1 to 1, but they do have to be 1 to 1 among monster hunter fans more or less... and it's a gigantic assumption to assume it should be with essentially everything else falling around it.

If Monster Hunter really was that Popular... Capcom would just create their own handheld.