Nintendo boggles my mind. They could release the original Super Mario Bros on iOS, which would require almost no new programming, sell it for 99 cents, and make several million dollars. Perhaps even 20 or 30 million dollars. When that cools down, they could sell Super Mario Bros 2, and then 3, and Zelda. SNES games will take a little more attention to get smooth controls, but other people have done a pretty decent job with some of the titles.
I'm sure they have their reasons, but then they release that Miitomo "game" and totally drop the ball on Super Mario Run, and I'm left here scratching my head. The marketing was so poor on the Wii U that tons of people didn't even recognize that the Wii U was a separate console from the Wii. At least things seem to be going well with the Switch so far. I think Nintendo's glory days are behind them though.
It's not "no new programming". Not by a long shot. And then whenever a major iOS update occurs, you're at the mercy of Apple to figure out if anything needs to get a major overhaul (of which to no small number of devs... it wasn't worth the effort, so they quit). Even if you manage to smooth that out, no telling what's around the corner.
Not having physical controllers is a huge detriment. iOS isn't a popular enough gaming platform that the masses will have external controllers. It has to work with touch controls, which my experiences have been fairly lousy. They'd have to put in a lot of work, but still have to give Apple a 30% cut on all sales.
Nintendo still has their own line of hardware and they want to hold on to that advantage, and push people to buy that. The same reason why Apple has never looked back at licensing OSX, nor bothered with licensing out iOS to other manufacturers. They want the vertical control so they control both the hardware and the software. Ditto with Nintendo, letting THEM call the shots. People not knowing the Wii U was separate from the Wii reminds me of Ipod users who had to be told products and songs will work on all MP3 Players
and Ipods, even though the tech community full well knew that Ipods were MP3 players.
I wish Super Mario Run would get a sequel, but I hear it didn't sell well (too many people were surprised they couldn't get the full game for free

), so I'm not counting on it. I can at least continue to buy Nintendo games on hardware to get the games I'd like.
You tap the bubble to send you back. Sometimes that's the only way to fully complete a stage
By "fully complete", I presume you mean collecting all of the pink, purple, and black coins? AFAIK, it should be possible to collect EVERYTHING without bubbling. Even with Mario. However, switching to another character would certainly make some parts smooth sailing.