It's nothing new and not a secret to most users in here. Mainly newer ppl may not know that. Rebranded tvs have been around for years. Also just cause a tv uses a part from another manufacturer doesnt make it that manufactures tv. Even if it was/is, it will just as you say, be a lesser model/tv. No point in buying a lesser quality product unless your on a budget and even then the saying goes, "you get what you pay for".
Companies switching out panels is also nothing new. Its been going on awhile also. Companies have the right to change any part at any given time. Is it right, no, but it is business. Thats why the panel lottery got so famous a couple years back. Nowadays ppl just accept it. Ppl can complain all they want, the companies will not change. As you said, its what keeps up the profits.