[Crazy Jetty]

Store exclusives are something the store wants. It's not the toy company that decides "Hey, let's make an exclusive for Walmart!"

Target comes to hasbro and says "We want to have a figure/doll that no one else has. We're comissioning you to make a special Transformer/MLP that only we can sell."

Why? It's an attraction to their store. Collector/parent goes into their store for a toy no one else has, and decides to do the rest of their shopping while you're there.
That's why store exclusives exist.
It's not some conspiricy to drive collectors insane, or make toys difficult to find.

As for TRU, it's only logical that they would get their share of exclusives, being a genuine toy store.