Hello everyone. I posted an enhacement suggestion to bugzilla and was advised to discuss it here: http://bugs.gentoo.org/show_bug.cgi?id=282491 (please read with comments).
The idea is that package tree physical structure must correspond to logical structure. E.g. package kde/games/tactics-and-strategy/knetwalk instead of kde-base/knetwalk, and kde/games/all instead of manually managed meta-package or set @kde-games (kde/all == @kde, kde/games/arcade/all == @kde-games-arcade, ...). Jeremy Olexa already answered me in bugzilla that this is not new idea, but I'll submit my suggestion here anyway as a "voice of crowd". :) I'm just home user with about 2 years linux experience, do like gentoo, but with exception of this inconvenience. Best regards, Dmitry