Games on mobile platforms can work. They just have to be built around the hardware and the touchscreen. A port of a console game won't work obviously. But I say it's bullshit that you can't experience Mario on a smartphone or tablet. I mean, Nintendo made everything with Mario and a game like Mario Party would work flawlessly on mobile platforms. You just have to make mini games that make good use of a touchscreen.
So, if Nintendo really wanted to, they could bring quality games to mobile platforms. It wouldn't decrease their brands, it would instead increase their value. If the games are good, Nintendo can reach people who don't own a gaming console at all. If they like the games, maybe they will consider buying a Nintendo console.
Nintendos approach on the matter is very short-sighted if you ask me. Quality games will always do good for your company, no matter on what platform.