Without reading the other posts:

-It didn't have the "cool factor". It just looked like a kid's toy. If you wanted power, you got an Xbox. If you wanted online gaming, you got a PS2 or Xbox. If you wanted an incredible library, you got a PS2. The GameCube was just in a weird place.
-It had the worst version of multiplats, by far. Some games I bought for the 'Cube and had to return for the PS2 version. They were just missing too much content.
-It always got new multiplat games later than be PS2 and Xbox.
-The PS2 pretty much had the generation won before the GameCube even hit the market. Based on a magazine I had at the time (PSM), the PS lead was insurmountable and people polled only considered getting an Xbox or GameCube as a secondary system--and not many were even going to do that.
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This was back during gaming's "edge lord" phase and the Gamecube looked like a purple lunchbox (I'm half joking please don't take this comment too seriously lol).

Can't believe people are calling the Gamecube "ugly" though. The PS2 was ugly. Even the Xbox was kind of ugly. The Gamecube looked cool as hell.

Contents of this post were spam and have been removed.

~tads12

1. Microsoft took the FPS market which was one of N64’s greatest strengths. The Rare buyout never paid off that well, but it did deprive Nintendo of Perfect Dark.

2. Nintendo doubled down on the “kiddie” image that was plaguing it ever since Mortal Kombat with the purple lunchbox design,  Wind Walker art style, and that awful Mario Sunshine ad. I used to think these weren’t such a big deal, but I think otherwise now.

3. No 2D Mario? This is Sean Malstrom’s complaint, but if you look at the sales of New SMB and New SMB Wii, maybe legit.

4. Bad third party support: I think there are lots of reasons for this, N64’s poor performance took all the energy out of GameCube from a business perspective, there are rumours MS moneyhatted some games into PS2/Xbox exclusivity, and you’ve got the button layout and disc size complaints mentioned before. I will add that it was way better than the third party support on N64, just not very good.

Yeah, I was going to point this out as well.  It released too late.  The PS2 had already sold 10 million consoles by March 2001.  That's 6 months before the Gamecube even released.  Gamecube and XBox were both walking into a meat grinder at that point.

Sony did moneyhat many 3rd party games which helped its sales snowball. It simply choked out the competition with their own library.
Which is a shame because GameCube was a great console.

1. Lack of momentum from the Nintendo 64
2. Mini DVDs and no DVD playback
3. Lack of some third-party heavy hitters like GTA and Final Fantasy
4. Lunchbox design
5. Not launching with a 3D Mario game
6. Most notable software support fizzingly out by the second half of 2005
7. Microsoft's debut console (Xbox) being more appealing than most Sega consoles. This, in addition to PlayStation's dominance, was a problem.

Not having games like GTA3 hurt, but Nintendo hardly ever gets the same level of multiplatform support as their competition. Nintendo themselves should be seen as the main variable that went wrong.

The GameCube was basically the N64-2 as far as Nintendo's software support went. Most of the best-selling GameCube games (Super Mario Sunshine, Double Dash, Wind Waker, Melee, Mario Party, etc) were basically less-revolutionary successors of N64 titles. And the N64 wasn't that popular to begin with, so getting a few more multiplatform games was not that big of a deal, especially with Rare out of the equation after 2002 (4 of the top 10 sellers on N64 were Rare games).

It also didn't help that Nintendo seemed to give up on the GameCube halfway into its life. Look at the N64; it didn't do amazingly, but many of it's biggest games were released in its fourth year or later (Super Smash Bros, DK64, Majora's Mask, Mario Party, all the Pokemon games, etc). How many big GameCube games were released from 2004 onwards? You had Pokemon Colosseum, more Mario Party, and Mario Strikers basically.

Basically, nothing was going to beat the PS2 that generation, and it didn't help that Nintendo seemingly blew through all their core franchises within the first 18 months of the system's lifespan, then seemingly abandoned it in favour of focusing on the GBA.

However, one thing that did stick in my mind was when I took my GC to my local youth club so my friends and I could have a little Smash Bros tourney - I had purchased the black version instead of the more common purple one, and I remember my friends being shocked at how much cooler the black version looked, and wondering why Nintendo hadn't made it the standard design. I mean, I'd like to believe that the GC didn't fail just because it wasn't emo enough for gamers back in the early 2000s, but...

If I remember right, Gamecube had the image that it is built for children, although you also had great games for adults. Super Mario Sunshine came too late and was nevertheless too short and unfinished, Zelda Wind Waker wasn't the game everybody expected after Ocarina of Time/Majora's Mask. I think there wasn't a true must have system seller in the beginning. Sure, you got Metroid Prime and Resident Evil 4 later on, and that was the time I was really thinking about getting a Gamecube, but at that time I already had so many great games on PS2 I had to play (Tekken, Gran Turismo, Metal Gear Solid, Final Fantasy etc.) that I just skipped the Gamecube.