A short test seems to indicate that this change does not reduce the usability of the [cpan://...] notation for module searches, as CPAN seems to automatically do a similarity search if no exact match is found:

http://search.cpan.org/dist/DBI vs. DBI # direct match via [cpan://DBI]
http://search.cpan.org/dist/test vs. test # fuzzy match via [cpan://test]

Update: Weirdly enough, for the second link, search.cpan.org does return different results, the current link style finds the 5.6.2 Perl distribution of Test, while the /dist/ link finds the 1.2.4 standalone distribution of Test.