Ummm. They were planning on using CD's instead of the cartridge for the successor to the SNES but due to the partnership falling through with Sony, Sony released the Playstation with CD and Nintendo then had to put something on the market quickly with the N64, so it kinda fell back to cartridges.

They chose the mini DVD to try to stop pirating with the gamecube. It didn't stop it, just hindered it at first.

The Wii used DVD, and now the Wii U uses a semi proprietary blu-ray.

Much of it has been said to try to reduce piracy.

Because pushing a media center as a console didn't work for Sony in '06 or Microsoft in '13. At this point the Wii U not having a DVD/Blu-Ray player is a non-issue. You already have one in your house somewhere.

Since the mini DVD and semi proprietary blu-ray aren't their own they are sharing money. They also share the money with ATI whome they have used as their GPU chip sets since the GameCube. Plus IBM for their processors for quite some time as well.

64DD was a huge mistake. They could've still salvaged that gen had they ditched that and went for a CD-ROM add-on.

The issue wasn't the vendors, I'm sure Philips would've been happy to give them CD drives, and if not them probably 10 other vendors.

The issue with CD is I think Miyamoto and several others at Nintendo hated the format and they twisted Yamauchi's arm on it, but in doing so they basically handed the console market on a silver platter to Sony. That's why game designers should not be making business decisions. 

Actually ps3 being a bd player well to Sony thanks for them winning the format war and it really was a selling point for ps3 at first, the problem that instead of bd replacing DVDs, streaming came and is becoming dominant, with bd doing well but not reaching the omnipresence DVD had. But this is subject for another thread.

Nintendo tried to push Wii U as a media center though, as TVii was really important on their first marketing, and for that it's strange to not have bd playing capabilities if already have aa bd reader inside your system .

Nintendo seems to worry so much about piracy that they go suicidal to prevent it. There's a point when its worth building your system to be piracy proof, because really, the only thing between a new protection system and a new crack for that protection system is time.

Because every technology invented after 1889 is evil and they want to have the least evil console possible.

Because they honestly believe being "different" makes them unique, all it does is make them behind the times.
Behind the times for media formats,
Behind the times for network connectivity
Behind the times for hardware specification
Behind the times for developmental capacity

Because they fear being too similar to other, more standard media formats would be all to easy for piracy.

Meanwhile the WiiU is the only Nintendo console that hasn't been pirated... yet (only a matter of time before the first ODE is released)

Everyone I knew who had a ps1, ps2 or psp has lots of pirated games. I think it really sold a lot of consoles on the fact that games could essentially be free after a small mod. And now the brand is set in people's minds