I agree. The problem is that the work truck won't hold its value nearly like the nicer ones with some amenities. And that's fine. However, like you said, if you want one thing it comes in a $1500 package and isn't modular. You'd think that by modularizing things, they could open the doors to more GM accessory sales. Then again, when they sell a $150 sub/amp enclosure that takes up half your under seat storage for $800+ and expect consumers to think that's a fair price, that's where that theory becomes defunct.
Big businesses fail the comprehend the concept of volume sales. You'd sell more accessories if you made them around the same price as their aftermarket competitors (who make a better product by the way). But instead, they sell inferior products for 2-4x the price of a quality aftermarket one. Take the under seat rear storage. Rough Country makes one for $120 and Du-Ha for $180. GM's lowest one was over $500 and wasn't half what these were.
How about lighting? Add additional 'placeholder' spots in the battery power distribution block and then sell good light bars at a reasonable price that just plug into those and form fit into their grills/facias. Easy money.
Again, if they could modularize these things they could make an absolute KILLING.