I'd argue that the "money machine" has been losing steam for years now and that their hiring of these boys is an attempt to keep their heads above water - i.e. they realize that the "Olsen Twins" is now a valueless brand and that they should go with what they know and market a new set of twins.
That might just work twice - but it shows that they are already out of ideas.
their Mary Kate and Ashley line of clothes sells very well at Wal-Mart. A lot of their stuff is actually very conservative, so my daughter likes it and so do we, and we can actually send her out without her being dressed like a little Britney Spears.