Oh yeah, Nintendo knows they not only hold the ball but own the court to play on when it comes to gaming IPs that gamers want. They marketed themselves nearly perfectly in the mid to late 80s with the NES. It helps they held back competition with anti-competitive practices but seriously, what competition did they have?
The Atari 2600, still supported by Atari, was WELL beyond capable of producing games with graphics and sound that gamers demanded. The Atari 7800 was much better off in the graphics department but Atari messed over developers with the same audio capabilities as the Atari 2600 (then waiting years to release the console didn't help because they didn't want to pay outstanding development costs).
Sega was at the will of Tonka as far as getting the Sega Master System into gamers hands. Obviously Tonka was more interested in keeping their dwindling marketshare with their metal work vehicles and other endeavors to stay afloat - Sega was a 5th thought at best for them.
Sega was fighting not only Tonka's lack of experience in marketing a gaming console (they sucked at marketing action figures years before too) but also the anti-competition practices of Nintendo and well, Sega's HORRIBLE box art didn't help. If I remember correctly, SMS games were also $5 to $8 higher than NES games (about the same price as Dragon Warrior or Final Fantasy on NES but it was a shooter game on SMS - not the same perceieved value).
Halcyon never got out of the starting gates, maybe a few prototypes were available around the time the NES hit.
Computers were prohibitively expensive, even a Commodore Amiga 500, with monitor was STUPID expensive.
Nintendo's true competition during this time was Commodore's 64, an aging computer that they were able to get lowereed in price over the years to be competitive. It being a computer it was not considered competition to Nintendo so they were able to get in stores alongside Nintendo products without any problem.
Commodore suffered the same thing Sony would with the PSOne though. No inhouse creations to sway gamers over and relying nearly 100% on others to make games for the computer (I don't think Commodore ever released a game themselves, choosing to pull a business approach like Microsoft did with Windows and Office suites).
We as gamers really only had one affordable option - Nintendo.
Now that competition is much higher, they can fall back on nostalgia and keep those high price tags for very little game going that no other company can.
For me, they are simply out of my price range and my tastes in games have changed. I find more enjoyment with slower paced adventure titles like Maniac Mansion or King's Quest now than my skills will allow me to enjoy something like the latest Mario platformer.