Most switch racks I've seen and the one proposed does not have a disconnect for each starter, that is why they use switch racks, so they can save money, with another 15 disconnects there is no way you would save any money. They just put in combination starters and figure you can work on the starter with it turned off.
With a switch rack you have to turn off the entire rack to pull a starter or you will have exposed 480 Volt leads as you are pulling the starter off the rack. Unless you decide to change out just the guts, which normally on a switch rack when the starter goes bad you need to change the whole box.
On MCC you just pull the bucket, work on the bucket if can be or put in a new bucket.
Of course following all applicable safety precautions in each one. No matter what, with a switch rack you have 480V leads dangling in the air while your starter is removed.