It wasn't my opinion that they didn't care about trade in fact they seemed happy and not violently moralistic when trade was pumping slave/conquest silver into their economy. Yes I think that economics is important since it's one of the main windows into seeing the stresses on a nation.
I would definitely agree with you there, but that is not the same as motivation.
Going by my last post, I think you can guess that the stresses that were breaking China apart had a lot to do with economics. Many of the revolts that just destroyed 19th Century China had a lot to do with rural poverty. While China was quite wealthy in the 18th Century, by the 19th century, there were too many people, too few land, and no new technological invotions to spur agricultural surpluses. Consequently, that lead to rural poverty, displaced people and a general decline in the whole economic system since in pre-industrial economies agriculture is essentially the economy. And that means the urban, and commercial economy will decline as well since those sectors are dependent on the agricultural sector.
This was further exacerbated by social tensions caused by the Manchu ruling class, and civil service examination candidates. educating and training someone for the civil service examination was stupidly expensive and took a lot of work and dedication. The problem is, is that Manchu's were able to take a very easy examination to get government posts while the amount of government posts stayed the same/declined. This meant that it was far more difficult for all those elites to get a position while it bred jealously and hatred for the Manchus who had an easy time. Not to mention that the government was more and more poorly run due to the lack of government officials.
As you can see, the peasants couldnt afford British manufactured goods and the elite families were spending all of their money on training their sons for the civil service examinations. And that was by no means was a sure thing either. However, that was the road to prestige, status and monetary success, so famiilies put all their effort into it. Why then, would they waste money on western clothes and goods when it was neither prestigious or seem all that useful for the advancement of their family? Does a clock better prepare someone for the civil service examination? No, in China, they were fascinating curious that the wealthy bought, which can be best seen in my previous post about the Qianlong Emperor.
What that all means is that there was no market for British goods. Britain, in their ignorance and arrogance could not understand this, thought that China was demanding silver as some devious scheme. There was no scheme though. There was no demand from the government to only accept silver. The Hong merchants in Hong Kong only accepted silver because that was the only thing the British brought with them that China wanted. And if you remember why the Qing Emperors regulated the trade much more than the East Asian trade from another post of mine, then I think you will understand that it really wasnt about unfair trade practices to get one over on the British, but legitimate security concerns due to British traders actions in China and Britain's actions in India.
Going by the societal misery and dissafection in the above paragraphs, peasants were poor, the elite's path to success was expensive and being increasingly reduced, and conflicts between different groups, that there was a market for Opium. The Hong merchants, officials, and everyone else enthusiasm for the trade should make it clear how ineffective the Chinese government was at limiting even an illegal trade. What this means is that if there was actually a market for British goods besides opium, then no matter what unfair trade practices, the merchants, the local officials (bribes), and the Chinese populace would have found a way to enrich themselves with the British trade.
All of that was a great deal of economics and related to economy, but hopefully I have demonstrated in my previous post that the moralist faction in the Qing government and the Daogong Emperor equally or largely put the crackdown on Opium because opium was seen to be a morally degenerative drug, China was declining, and therefore, the moralists and Daogong came to the conclusion that Opium was the root of all of their problems.