how is that part of the development model? they are still branches, wether that information is stored in the repository or not.
So if you have a repository A, and copy that to B and C (deleting A), which one of B and C are branches and which are non-branches? Things which have been given branch-tags in CVS are clearly branches from a certain main development line, and have specific names, and therefore sit quite well in a "branches" directory with those names as sub-nodes. But the Pike/xxx are not branches from any main development line, they _are_ the main development lines.
how would following the svn convention change the development model?
To follow the svn convention would require us to have a "trunk". But we don't use a single trunk.
svn convention:
branch branch branch / / / trunk ----------------------------------------->
Pike model: branch / 7.2------ / 7.1 ---< branch 7.4---- \ / / 7.3-------------< \ 7.5------
what difference does it make?
What difference does it make to you, since you bring it up? How would you like things to look? Everything under /branches/? Then what would the point of having /branches/ at all be?