I don't think iOS is the "undisputed portable king" just yet. Porting traditional games to iOS loses some measure of control accuracy, though this could be mitigated with a portable controller at some point (like we're seeing from Power A and Nyko for Android platforms later this year). It's a more convenient platform; it's easier than carrying multiple devices on your person. Games are also much less expensive.
However... a market for traditional handhelds continues to exist, even if it is smaller due to market shifting to phones & tablets. Some players, notably core consumers, are going to want to hang onto traditional controller-style input without the need for a secondary peripheral. Nintendo still has its ace-in-the-hole with its first-party IPs, which generate hardware sales all by themselves. We can argue the long-term viability of the Vita (even though it's far too early to make fair judgments), but the 3DS has sold enough units to make me believe that the handheld sector will survive at least one more generation before mobile potentially wins out in a worst-case scenario.
I think I understand your frustration, since maybe you believe that resources for supporting the handheld market might be better used elsewhere, but I do believe that it's a bit hasty to drive all of the nails into the traditional handheld market's coffin at this point.