Undoubtedly?  I think people don't realize how involved Miyamoto was in Nintendo's rise to success.  He was responsible for several of the arcade hits that put Nintendo in the financial position to enter the console market (most notably Donkey Kong).  Then, he created the games that made the NES worth buying.  What caused the video game crash in North America was not hardware.  There were plenty of quality systems to choose from (perhaps too many).  The real issue was software.  Everyone was looking to cash in on the video game craze, and created tons of games that make the Wii's shovelware look like pieces of art.  The terrible games completely dominated the few solid games in the year leading up to the crash, and long story short (I have a dozen pages on this if you want to read more) the video game industry lost the confidence of both consumers and retailers.

Thus, what was really the critical part of reviving the video game market was not some super awesome piece of hardware, but rather, great software.  And who was responsible for that?  Miyamoto, of course.

So, so. It took clever hardware, good pricing, smart marketing, good software, and more smart marketing. You are correct about not needing super hardware, but there is no doubt Gunpei made a huge impact on Nintendo's decisions with how to design, gut, and market their hardware.

I'm not in any way trying to belittle Yokoi's accomplishment, as I see him equally important to Nintendo's rise.  However, to claim he was far and away the largest contributor to the company's early success is ridiculous.

No, it is not. Miyamoto did not create the philosophy that Nintendo stands by to this day. A business model that would stand for any company in the world. This man knew what he was doing from more than just a hardware standpoint. He sold a Game Boy to me, and millions of others over the far more powerful hardware of the time. We all bought the NES over more powerful hardware. And DS and Wii (one under his design as well as his philosophy) are going to break all sales records set before them. Both follow his methods and philosophy. Miyamoto makes great games, helped mold amazing characters, and has done wonderful things, but without him, Wii and Wii Sports would still have happened. The DS (and its design) would still have happened. Wii and DS would still be amazingly successful and that is because the company had Gunpei's philosophy to follow.

When you consider their similar contributions early on along with Miyamoto's continued support of the company, Miyamoto clearly establishes himself as more important.

No, even more than ten years after Gunpei's death, there is no disputing this fact:

If you own a Wii and/or DS, you bought Gunpei's product. Period.

That is impact Miyamoto would kill for. To be around today, and still making good business is one thing. But to be dead for more than a decade and still have a whole company following the path you laid down is making a man immortal. And that is why Gunpei is far more important.