Colour reduction is the use of automatic tools to make a photo or hi-res digital art look like pixel art. It's not allowed because you aren't doing hardly any work yourself.

AA is pretty much one of the fundamentals of Pixel Art. It's not always necessary, maybe for stylistic reasons, but generally it's beneficial to a piece.

Also a good idea to link to the piece(s) you're talking about.

I can't believe to imagine you'd have problems with a piece! And didn't see the slightest hint of a suspicion of color redux in your gallery.
Was there a problematic submission that you removed?
If so it's ok to show it here, so we know what it's about.

I do think too that some of your art could benefit from AA, but well, you're talented enough to know what you do and do as you like! However if you experimented it, you might realize it can actually help that crisp sharp look. ;)

As you know, art is not about rules. A collaborative project such as a web gallery couldn't work without some, but that has nothing to do with art itself.
Art at the basic level we practice it here (meaning the visual level, and level not meaning quality) is all about inducing the viewers eye/brain to see stuff that isn't really there. This is the one cause of this vibration we feel in front of a good piece. Pixels are one powerful tool to achieve this, and pixel art techniques help make it so. In the end what the art says to the viewer is the only judge.
There certainly are fashion trends too. It's even visible on PJ: many 'older' pieces (5 yrs old at most!) have a different feel from today's average, partly through the use of different techniques.

[/rambling]

One last thing about your work. The ease with which you make these brilliant pieces makes me think it's time for you to explore out of your comfort zone. As someone said in a comment, you could be awesome.