The 3DS has failed to attract any Western 3rd party support and is not close to matching the DS success despite seeing sequels in various Nintendo franchises. I'm not going to mention the Wii U, I guess that's obsolete in this case.
And who's Adam Sessler and what is TekHD? If you think that he's right, don't you agree that Nintendo's strategy of not releasing ports on these platforms is an example of bad management? I'm not exactly sure whether it would be a wise decision to release their old titles on Android/iOS, but I think the way they handle the Virtual Console could be better.
The Wii U is struggling, no question about it. But saying that the 3DS is not close to matching the DS success is a bit of a misnomer since the DS got multiple generations of pokemon, it had over 8 years of support, and you say that the 3DS got multiple sequels, but they just really started their support in the 2nd year of the 3DS, and we're only in year 3. If we check a year from now, after Yoshi Land, Zelda, Smash, and Pokemon are out, I think we'll see the 3DS sales spring up and match up with DS sales comparably again. They also have a couple of more tricks under their sleeves like a 3DS Megaman man modeled after Megaman in Smash. (I have no idea if they would do this, just saying they should.)
And I brought up Adam Sessler because its an easy way to show that the people who constantly say that Nintendo should bring their titles to mobile are shortsighted, like you have said. And I don't think its bad management, since selling on mobile directly interferes with their ability to market and sell their handhelds. And the mobile market is comparatively small, from Jan. 2013-March 2013, the entire mobile market for video games (Android, iOS, BB, WP, etc.) was $100 million. (Nintendo as a company had $9 billion in revenue in the last fiscal year) Nothing to sneeze at, but that was the entire market, and Nintendo trying to sell $5 on the NES version of Super Mario Bros. in a crowd of free to play, pay to win, and $1 games would probably not justify the costs of getting a game like SMB to run smoothly with touch controls.
Also, just as Nintendo needs to focus on converting wii owners to Wii U owners, they also need to convert DS owners to 3DS owners. According to this chart, its the U.S. who lags behind on this.
I think two games(well, three games technically) will get people converted, Pokemon X/Y, and Smash 3DS. After those games are released, I think we'll have a better picture of 3DS selling less or more than the DS.
Edit: As for western 3rd party support, they need to figure out how to make games and sell it on the 3DS. Its up to EA, Ubisoft, Activision, and who ever else want to sell on the system to figure what the 3DS consumer wants. A 3rd Party western developer can blame Nintendo all they want, but they're the ones losing on potential profit.
The answer is probably releasing smaller titles on the eShop, I just picked up gunman Clive the other day, and its a neat little title I like playing from time to time.
There's no reason for Plant vs. Zombies to not be on the eShop, and that's on EA and Popcap, not Nintendo.