The can't just expand an order of cars on a whim, they have to have the budget for it as well.
The R110s were test trains, therefore mass producing would've been stupid. Especially since they were never planned to run long term anyway.
The R160 order was originally supposed to be 1,700 cars. It was decreased to 1,662 because of budget problems. Especially since the economy was going down in 2008-09 anyway. But had those extra cars been ordered, their yard placement would not have changed.