Lambos aren't limited, though, not even the Superveloce or Superleggera variants. They'll build as many of any model as they can sell. It's more like making sure a person is serious about their commitment to being a limited edition Ferrari owner (while padding their pockets at the same time). But I guess there are worse things than being required to buy a cool car so you can potentially buy a cooler car.
It's not perceived, it's actual exclusivity (exclusive to loyal Ferrari customers), it's just a forced situation.
and yes, you can sell the "lesser" 488, but I imagine it would be wise to wait until after the GTO is in your garage.