The point about high levels being "aspirational" I think is very true. I think a lot of us have the "power fantasy" of our characters making it to 20th level, and even if it doesn't happen it is part of the imaginative experience.
There were a few other things I found interesting in the notes:
- Crawford's notes about focus groups: In other threads your seeing this belief start to propagate that surveys are literally the only market research WOTC does. Its not, as Crawford notes here, they use focus groups as part of their research.
- That 4e games also end at 10th level, even though the level range is now 30 and I think 4e had some of the best high level support of the last 3 editions. I think that really does paint the picture that games end at 10th primarily for length reasons or narrative ones, games just end by the time your getting to those higher levels.
Ultimately I do think high levels have a place for that occasional one shot, and for the power fantasy noted earlier. However, does it really need to be 20 whole levels? I mean that's literally half of your levels as "dead weight" in most campaigns. Seems maybe like 15 levels could still give you a lot of the aspirational aspects, make it a bit more likely groups can get to the top, and then you don't have 10 levels you have to figure out stuff for, and so can make the higher levels more balanced and easier to design for.