I would say no ...
In my opinion, the core philosophy behind the Nintendo DS and Wii was to build systems that were unique in the market and to not get caught up in the endless graphical arms race that was driving up the cost of videogame development. In ways you could say that this strategy was developed by Nintendo doing “soul searching” trying to understand why their portable systems were popular and their home console’s weren’t; and the realization that the Gameboy line thrived off of being a unique product while the Gamecube struggled because it wasn’t adequately differentiated from the XBox and PS2.
As far as user interface improvements go, there has been significant effort into improving the 3DS. While they are often minimized, the 3DS slide pad is actually a very good approximation of an analogue stick and the introduction of motion controlls certainly add some options to developers. On top of this, the 3D screen offers the same kind of wow factor to users that motion controls did with the Wii; and much like the motion controls they do so without requiring expensive software development to take advantage of it.
In terms of processing power, the Gameboy was (roughly) a portable NES, the GBA was a portable SNES, the Nintendo DS was a portable N64 and the 3DS appears to be a portable Gamecube; which means that the underlying technology has remained (reasonably) constant over time.
Realistically, the only reason I think that people truly believe the 3DS is such a depature is because of the price; and I believe that the price difference has as more to do with countries destroying the value of their currency as it does with the 3DS actually being more expensive.
