I've heard that some Game Boy games could be played on a Game Boy Color, which gives the game color. Who else thinks that Nintendo should update these existing games to include the color option?

Do you mean original Game Boy games, upgraded to have full GBC support? There were a few of those. However, when one of those is released, Nintendo seems to like to choose the GBC version (Link's Awakening, Wario Land II). Then again, they did choose Tetris over the DX version (maybe just because the original is a gaming icon?)
But all original Game Boy games could be played on a GBC with one of the default palettes applied (okay, except for I think literally one or two obscure Japanese games that would crash on a GBC).

I don't really know, I only recently found out about this. What I do know is that some original Game Boy games- I only know of Kirby's Dream Land and Metroid 2- could be given color by putting the cartridge in a Game Boy Color. I honestly don't think this idea is that crazy- after all, they included the virtual Game Boy (Color) background when you open a game when holding Start or Select. This could be implemented similarly to that.

I recently found out about this too. I put Super Mario Land in my Gameboy Color, and it did assign a small color pallette to the game. Blocks looked yellow and the sky looked blue. It barely made a difference, but it was rather neat.

I don't mind either way. If we get the colorless version, it may feel a little more "authentic" because it is closer in appearence to the original, but if we get the colored version, it is slightly enhanced. So it's a benefit either way, at least in my opinion. Definately having the option to change it would be nice, but not needed.

A color version of Metroid II would have helped. That game was easy for me to get lost in because everything looked so similar. I heard the color version, which I never played, made navigation a little easier.

Yes, yes they should. I remember playing gameboy games on my GBA and it giving them color. I was disappointed that you couldn't use color with GB games on the E-Shop.

Nintendo will update the 3DS eShop to include native "Super Game Boy" support for Virtual Console games.

It'll just cost you $2 per game to make the upgrade!

Plus another dollar to unlock new borders.

And then one more dollar to unlock the save state feature in this newly upgraded version of your games.

A dollar for an option to have the borders animated.

The GBC could only initialize the palette when booting up original Game Boy games. It can't change the colors midgame for B&W GB games.
I've heard some say a color (DX) version of Metroid II was planned but the only colorized Metroid II I've seen is an unofficial ROM hack (and I've heard these unofficial colorization hacks were pretty buggy as well).

Oh really? Didn't know that. I downloaded Metroid II last year and was complaining about it to a friend of mine and he said he thought it was weird they didn't realize the color version. I assumed he meant there was an official color version.

The GBC would give original GB games a high-contrast color scheme for visibility on the original GBC's dark screen that had no built-in lighting.
It would color sprites differently than the background.
This can actually cause inadvertent spoilers in some games. Like if you play the original (non-DX) version of Link's Awakening on a GBC, when you get to the Face Shrine, you will be able to see the living Armos Statues because they will be a different color.
And Metroid II is the other example I remember: when you reach the room with the Varia Suit, its hidden location will be immediately revealed (it was still pretty obvious something was hidden without the spoiler, but that's besides the point).

The ones that can be shoved with a shield are the living ones, and can be shoved without activating them so this one isn't a big deal.

@KingMike Remember, this would be OPTIONAL.

This might sound weird, but as confusing as Metroid 2 is, I like the black and white. Combined with feeling of loneliness and creepy atmosphere, it feels like an old black and white horror film. Try playing late at night, with the lights off.

I'm only saying the method the GBC uses to "colorize" a monochrome game gives an unintended spoiler to the original puzzle. Not debating whether you actually need that assistance.
And I suppose you could disable that by pressing whatever key code on the Game Boy logo screen changes the palette to pure black & white.

I downloaded Metroid II in December and played through it. I really enjoyed the atmosphere and only got lost really one time. It took me about 8 hours to play through the game. I played it over the week of Christmas.

Brilliant! Nintendo will be rich!