But the twins are moving away from film after their disastrous New York movie, aren't they? Because you're right; they can't act. Now it's just about keeping that money machine working overtime by going down different revenue driving avenues.
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.