I agree, although by native clustering I meant that the Postgres engine itself should support it, much like incremental vacuum was eventually built in.
pg_repack is a fork of pg_reorg (which has not been maintained since 2011), by the way, which has become the de facto replacement. No idea if the code is in need of cleanup or not, though.
Tell the community - pg_reorg could be cleaned up, improved, and merged into core... and should be!