But what can we, as gamers, do to put enough pressure on them to change for the better?

But by not buying Federation Farce, what if it leads to the Metroid franchise being canned for good?

https://www.nintendo.co.jp/ir/en/library/events/140130/

As for the quote, Iwata was the speaker, as he often was in these situations. I don't think it matters who says it, but the question is if this was Miyamoto's initiative, or someone above it. I'm going to assume that he either pushed for the idea, or did not disagree with it. For a couple of reasons.

He has been cited as one of the people within Nintendo who pushed for the Gamepad to be part of the WiiU from the beginning. If thats the case, then it's not surprising that he would be one of the people who would be more heavily invested in showing the audience the potential he saw in it.

Generally speaking, Miyamoto has a lot of trust and influence in Nintendo. If he wants something (within reason) he will most likely get the support of the company. Likewise, I don't see them going through with the idea of creating Gamepad based games or assigning Miyamoto to them if he disagreed with the idea. If he thinks it's a bad idea, they will probably listen to him. Take a look at how Nintendo tend to evaluate if a game idea is good or not, for example:
"Miyamoto, and Nintendo as a whole, do not use focus groups. Instead, Miyamoto figures out if a game is fun for himself. He says that if he enjoys it, others will too."
(That's from his Wiki page.)

Hiku said:

In either case, whether the idea to make Gamepad focused games originated from him or someone else, it's safe to assume that he thought it was a good idea and that it was his idea to make a Starfox game based on it, according to this quote:

"SM: We spent more than one year on numerous experiments using the Wii U GamePad, and in the initial experiments, we conducted tests with 3D graphics on screen using Pikmin and Star Fox systems as a trial.

While manipulating the RC aeroplane-like flying experience or creating the mechanism to appreciate the overall and partial views together, it made me think I should continue to create Star Fox utilising these elements. We fixed the basic form in six months, and then commenced the one and a half year development process."
http://gonintendo.com/stories/255628-miyamoto-elaborates-on-platinum-s-involvement-in-starfox-zero-ta?page=1

Yeah, the test players he may be refering to in the same article could be his friends and family, that his Wiki article mentioned. "He then tests it with friends and family."
Though I assumed that this is probably an old practice, and perhaps only regarding Miyamoto's own games. Would be surprised if their focus group don't extend beyond Miyamoto's friends and family these days.
But this was just to illustrate Miyamoto's influence in the company. Im sure they trust him a lot because of his history with the company, and value his opinion greatly. At least until he gives them a reason to doubt him.
A similar example can be Katsuhiro Harada of Namco Bandai. Mostly known as the producer of Tekken. But he's been involved as a director and voice actor as well. He has steered them unto a good path over the years. And he has quite the influence over Namco Bandai's decisions as well when it comes to games. A couple of years back, Namco Bandai did not seem to want to localize Project X Zone for 3DS. After fans asked Harada about it on Twitter, he eventually posted this: "I proposed localization of Project X Zone." He added that the company has "not decided yet, but It will be realized if I continue proposing." Of course he will propose it with a proper business plan, but none the less, it's pretty clear that he believes he has some influence on the matter. And I've heard from others in the industry that he does. (Zhi and Markman who worked at Mad Catz said so.)
It was basically the same thing regarding Xenosaga HD which fans reached out to him about. Almost a year ago, his initial proposal fell through, but he said he had other ideas, and when someone tweeted that "Even Harada can't make it happen", Harada replied with something to the extent of "I can." Whether he makes it happen or not remains to be seen. But I digress. I can only imagine that Miyamoto has the same, if not more, influence over Nintendo regarding games. And if they come with an idea to him, and he thinks it's not good, I'm sure they would take his opinion into consideration and value it highly. Would be strange to see him work on a project he doesn't agree with, to boot.

In either case, it looks like he thought Star Fox would be a good game for the "Gamepad project"

The "we" should be the "Mr. Miyamoto's software development department" that was mentioned at the end of the financial briefing, who's focus it was to produce titles that make proper use of the Gamepad.

They were put in charge of that task, and so they were the ones testing various game archetypes for this project. Miyamoto said that during this process, he came to the realization that he should make a Starfox game for this project.