Originally Posted by: WhuneWouldn't it make so much more sense to relate everything to the 12 tones instead of 7?[/quote]
No, because it leads to conceptual & perceptual confusion.

Yes, we eventually can learn that the chromatic scale is the complete palette, or total "background information" available. But to start making sense of sound & organize it into music, it is necessary (historically & conceptually) to grasp pitch specific tones in this order:

Root & octave: two tones, with the higher one exactly double in frequency.
Root, fifth & octave: Split the octave in half (ratio of 1.5 or 3:2) and you get the 5th.
Root, major 3rd, fifth, octave: Split the root & fifth in half and you get (roughly) the major 3rd.

At this point you've got a major chord: 1st, major 3rd, 5th, 8th. This is a big step!

Now we can "fill in the gaps". Most primitive cultures did this until they arrived at some form of a pentatonic scale:

1st, 2nd, major 3rd, 5th, 6th, 8th.

Or: 1st, 2nd, 4th, 5th, 6th, 8th.

See what's missing so far? Eventually, the early Greeks (and probably other early cultures in East Asia) figured out that you could further subdivide pitches into half-steps. That was a big step forward, also!

Finally, we fill in the gaps until there are only whole-steps or half-steps:

1st, 2nd, major 3rd, 4th, 5th, 6th, 7th, 8th.

The major scale. :)

The reason this was important historically & conceptually is that we are talking about sound being used as music, as art. So, the people studying it were trying to use it in a practical way, to sing songs, or make melodies on instruments. There was not necessarily a way to "get right to" something as complex or more advanced as the chromatic scale without going through the earlier steps.

Present day, we do in fact use the chromatic scale as our complete palette background from which to draw all musical materials. But when we teach beginners, we start with the conceptual beginning.
[QUOTE=Whune]
Chromatic - I - II - III IV - V - VI -VII -VIII IX- X - XI- XII
------------- A - A# B -C - C#- D - D# -E - F - F#- G -G#

Again, using Roman Numerals for scale degrees causes confusion because they are primarily reserved for chord progressions.

Hope this helps!