Congratulations man!

"But just because many people use a certain technique, it does not mean that it's still meaningful or the best possible technique."

People don't use color-keying because many people use color-keying.

I think you got quite many examples of how color keying can be a useful technique. And you've been explained more than once how providing pre-rendered rotated images can be useful.

You can see those techniques ARE still meaningful. And there is no best possible technique as an absolute idea - it depends again on who you are, what you can learn or cannot, what platforms you want your game to run on, what genre of game you're making...

Don't want to be offensive, I swear. Though you sound a bit pretentious (is this the right word? maybe rude would fit best...)  saying that SDL is outdated, and that Allegro is outdated, and that all the people round here (and also in other places different from OGA) use magic pink backgrounds and color-keying, as well as programmers using the libraries of above (me included), are just oldies and/or stupid people.

@GameProgrammingSlave: Being a programmer too, I must disagree with you. Both methods (what you pointed out as right and wrong) are neither good or bad in themselves, but have advantages and disadvantages which make them more suitable for one kind of use rather than another.

The alpha channel is useful (and I personally prefer it) but creates some speed issues with alpha blending. Considering SDL (which is far easier to implement than OpenGL and so is used by projects which don't need a lot of graphic power), using alpha channel on big surfaces can significantly slow down the game. You can choose to use it where per-pixel transparency or semi-transparency is specifically needed, but you can avoid it and use a color key (the magic pink!) where you don't need any partial transparency (which is the case of the majority of pixel art, as far as I know).

Same thing applies to rotated images (and could apply to scaled ones too): procedurally generating them at runtime is slower and often causes visual artifacts, especially with pixel art pieces. Thus, you should go with that solution only if you specifically need a picture to point in all the possible directions (or have all the possible sizes) whereas you should draw them (or render them, which was the case of the spaceships of above) in all the needed directions if they're a finite number (take a look at FLARE assets - besides being a very good example of pre-rendered art, they're rendered only in the 8 directions needed by the game).

At last, neutral light could make some objects look too flat, which in a game where they are always moving in the same direction (a sidescroller game, a topdown space shooter, ...) would be a useless loss. Of course, if your game would need the spaceship (or anything else) to rotate in many directions, neutral lighting would be the way to go.

Each game/game engine has specific requirements, there's not only one way to go... I'd suggest you to take a look at the comments by Duion in this thread (and at the whole thread in general of course) - he says more or less the same (actually slightly better than me).