Captain bloggs,
Don't get bogged down in the minutiae. The three points that I think an airspace system should be designed around are:
1. Be consistent.
2. Be logical.
3. Focus your resources where they will do the most good.
I used examples from the US airspace system to illustrate how these principles have been applied.
In Australia we have an airspace system( and broader regulation set) that is inconsistent, illogical and fails to focus on key risks. It is inefficient and if it doesn't cost you directly (as it costs dick) it will cost you in lost future employment opportunities or freedom to fly for pleasure.