encore and commemorative series

[tusko]

When I look at the new organization of the series, regional releases and what-knots... I notice that the Japanese Encore series is in with the G1 section.  This is cool.  I like seeing all the G1 molds together in my collection.
However the Hasbro Commemorative Series is not under G1. 

What's the rational for not merging these? The minor molding variation?
Thanks