They lost me at 2,5D
Like 3DS and Vita aren't capable of running 3D adventure games .....
While I do agree that the old approach of "Portable Side-Story" releases has been to the detriment of many handheld gaming fans (it's a rare exception that the portable game matches/exceeds the quality of the home game, and even when it does, sometimes you just wanted that damned home game to go,) it's a little different situation these days. When it makes sense to make the same game across all systems (like a Street Fighter or a Need for Speed,) they pretty much do because the systems can handle it, more or less. And when a franchise can support multiple products at a time like say Batman or Assassin's Creed or Castlevania, they make satellite games that offer new gameplay (which could be ported up to the consoles if they're good enough.)
It's not the ideal situation if you're looking at iOS or Android and seeing almost every game completely open to play on whichever platform you choose (and with home devices happening more and more with Android, we're seeing the line blur completely,) but when it's done right (and when a portable version of the full game would have been sketchy,) it's the best of both worlds. The
worst of both worlds is like with LEGO when we could have had the real games on our portables and instead we're getting shitty sub-versions that divide the workforce and de-prioritize the portable versions in every way, if the option in the office between half-assedly doing a game sort of like the home game and doing a totally different game I would totally prefer the spin-off game. Particularly when some of my favorite portable games are spin-offs of established home franchises (and some of the more interesting game developers specialize in portable spin-offs,) I hope publishers do consider this approach even though we have portables that can handle a port. Just
choose wisely, make sure you treat your portables as deserving platforms.
From what I see and what I know of this developer, I'm very much OK with this. Just do it right.