While that may be true, it's also possible that there are different target models for different projects to balance release windows vs larger projects. Some studios could still take on smaller projects designed purely as portable games that have assets that reflect a shorter dev cycle, and these could release more steadily while the bigger and more asset-heavy games are being developed.
Establishing a more portable-centric approach for SOME development that aims at sort of bridging the gap between handhelds and the mobile market could also encourage lots of indies to jump in and target the same.
Whatever the case, I don't think every Nintendo studio is suddenly going to start targeting the ceiling of what the hardware can do with every project. I could be wrong there, but it's not an unreasonable consideration.
I think when launching a new piece of hardware you're going to want all of your launch/launch window games to visually impress people. That's just the nature of console launches- people expect better hardware to produce better visual experiences. If there are going to be handheld-esque games which don't take much advantage of the system's hardware then I really doubt those will be showcased around launch time.
Also, as a developer, you typically want to make your product look as good as possible on the hardware you're targeting. Indie games that don't look like they're pushing the envelope visually still do typically use a good amount of the hardware power provided. HD 2D graphics actually require a hell of a lot of system memory, and can sometimes run at slow framerates even on high end hardware.
The point is, Nintendo (and most devs in general) don't usually develop games that use, say (arbitrarily), 50% or less of the "hardware power." Typically games take full advantage of the hardware they're on.
That's why I think they (may have) internally delayed the NX to March, and likely why they haven't revealed it yet. Nintendo's main statement they want to make with the NX is- "finally, all the games in one place!" and if they don't have "all the games" ready to show, well then they can't very well make that statement.