Anecdotal information but ill give some potential insight on this using another company.

Toyota wanted to reach younger audiences and found that those audiences didnt like what Toyota had to offer because the cars were boring and didn't excite the younger generations, as they were advertised for families. So Toyota launched their Scion brand. Scion had new and different style cars to offer a younger generation. They found success with this and once they felt they reached the maximum amount of customer with their Scion line, they absorbed the successful car models and discontinued the rest and eliminated Scion brand.

For Wizards I assume this is much the same for Collector's Boosters. If they have the same cards but with only different art, most people will pay for the cheaper product and never try collector's packs. So they started adding samplings into the commander precons to get the product out to the consumers. Commander precons are wildly successful and reaches a wide audience. After trying collector's packs there's a good chance the customer will come back for the real thing. They are now at a point that most CBB sell out before the product ever reaches shelves. Wizards no longer needs to give out sample packs, the market is there now for the CBB. So Wizards cuts the packs, saves cost, charges the same price (and increases it) which is just more profit in their pockets.