Could some of this also result from the contractual nature of using Chinese suppliers? I know that from my own experience with contracting, that proposing an improvement can be difficult if you also want to attach a fee to the improvement. How do you say, "I think your proposal is flawed, this way is better, but it will cost you $X more" in a way that doesn't feel like a money grab or an insult? It can be in your best interest to allow the flaw to stand, let the client notice and propose the improvement during the next round of contract negotiations. And so the only improvements a contractor can propose are those that do not cost substantially more then the established price.

Of course this is more for fixed price for fixed work contracting. Contracts with more variable pricing my be better. Maybe other contacting setups can alleviate this issue, but I haven't seen many that could work and that clients are willing to sign.