Thanks for that good a point. The MasonHQ site reads:
Version 1 of Mason (HTML::Mason) has been around since 1998. It is in wide use and is very stable. However it has not changed much in years and does not use much in the way of Modern Perl.
Version 2 of Mason (Mason), along with Poet, is being actively developed and has a much more modern architecture. If you are just starting out, we recommend you give Mason 2 a try.
So, in the course of remaking a webserver, while keeping much of the content, we focussed on Mason 2 in the first place. There are more advantages: Independence from the web server (doesn't depend on modperl, which is obsolete itself and, after all, does not run on Apache 2.4 anyway), automatic tests, to name two. Plus, when a version is actively developed, you can be sure that older versions get more and more neglected (security updates). This can easily be seen since Open Source projects haven't usually much capacity.
-- flowdy