Because tariff distort topologies. In the short term, if you drew a map
that used tariffs as the metric of your topology, the Atlantic would hardly
be larger than the Rhine. This in itself is at cross purpose with the
local implementation of CIDR, i.e. allocation of addresses to European
networks from a European block by the RIPE NCC.
If you look at the medium term, the perspective is even more interesting.
Deregulation will gradually take place in the next three years. It will
most probably result in lower tariffs for some lines, but not all, and
definitely not at the same time. Take the map which I mentioned above.
Imagine it printed on a fin sheet of elastic rubber, not paper. The effect
of deregulation is that for the next three years the rubber will be
constantly deformed, shrinking here and inflating there, and you are very
lucky if you can predict where and when.
To believe that this would not have some influence on addressing and
internetworking is at least shortsighted.