It's not far from the reasons you might choose to do internal betas and focus tests instead of test marketing every revision and variant you come up with from c

It's not far from the reasons you might choose to do internal betas and focus tests instead of test marketing every revision and variant you come up with from concept to product. If pilots were all released on HULU, then a season filled with middling to poor pilots would be reviewed as such. And then no matter how much a studio might try to improve the best of the lot, they'd have those negative reviews dragging down performance of the ultimate product. If pilot feedback is reasonably controlled, the studios have the option of polishing an almost-there concept (or more cynically: the best turd of the bunch) and not having reviews of its dodgy pilot dragging down performance of the final show.