I think Nintendo realized that if they support the older platforms theirs less incentive to upgrade. If Nintendo keeps dishing out Wii titles then consumers have less reason to upgrade. Also Nintendo has limited dev studios and with WiiU coming next year they have to get software ready. Also with all the 3DS games they need to develop it leaves very little time to tinker on Wii and DS.
In the end I think a large reason 3DS is suffering is because consumers don't see the need to upgrade yet. Example if Nintendo had launched Pokemon Black and White on 3DS rather then DS sales would have been far larger. Had Nintendo ditched DS last year and given 3DS more software at launch then we might have seen a different launch for 3DS.
I'm alittle dissapointed that Pikmin 3 and Vitality Sensor never came into being. Maybe Pikmin3 got ported to 3DS never loose hope. But in all honesty it makes sense for Nintendo to be bailing on Wii and DS. Hopefully consumers will see the need to upgrade, if not Nintendo is screwed!