Why not make Python 2 point to /usr/bin/python2?
because instead of:
| oh, look, /usr/bin/python is a symlink, lets use different 2.X version,
| I don't care about 2.Y anymore and I want 2.Z by default. What? foo
| application doesn't work anymore? Damn Debian developers, and they call
| their system stable!
we'll get:
| oh, look, there's /usr/bin/python2 and /usr/bin/python3 binaries
| so it should be safe to change /usr/bin/python symlink, lets
| do that, ... Damn Debian developers!
a *LOT* more often (changes between 2.X versions are not that big
compared to 2.X-3.X ones