Alright, I'll bite. First off, as I said above, plenty of objectively bad organizations like patent trolls and organized crime provide employment for some people, but that is not a reason to support them. You claimed that that was not your argument, but now you're bringing it up again.
Since you seem unwilling to do any research yourself (while asking a great deal of me for basically a throwaway comment), here are some facts:
1. In 2010, 'advertising mail' (in which junk mail is included) constituted $17 billion in revenue for the USPS, as opposed to $34 billion from first class mail. Direct mail advertising does provide a lot of revenue for the USPS, but not a dominant amount.
2. 44 percent of junk mail is thrown away unopened, and junk mail produces 5.8 million tons of waste in landfills annually.
3. I can't find any statistics or junk mail approval rating, likely because anyone who proposed such a study would get laughed at for trying to answer such an obvious question. I'm not sure what you want me to say here (I'm definitely not going to conduct the survey), but I think that based on the existence of things like spam filters, do not contact lists, and this entire thread that junk mail is not something most people appreciate receiving.
You seem to be arguing in favor of junk mail, because it generates money for certain businesses, including so far, the USPS, other mail delivery services, paper companies, the printing industry, and corporations which use direct mail advertising campaigns. I posit that junk mail is not a good thing, because it harms the environment, consuming over 100 million trees per year in the US alone and contributing to landfills. In addition, it annoys the vast majority of its recipients (even you admitted a successful advertising campaign will convert only a few percentage points of users above). Finally, the industries which you have named are not dependent on junk mail for their survival; even the USPS receives at most a third of annual revenue from the practice, and as I (and several others in the thread) have said, we would be willing to pay more in exchange for a halt to junk mail delivery.
If you have another argument to offer than supporting industry, please share it. Otherwise, I'm finished with this thread; if we're stuck on the basic point 'spam is bad,' we're never going to reach agreement.
Edit: I forgot to include my (admittedly found via random Googling) sources.
1. http://stateimpact.npr.org/new-hampshire/2011/09/27/how-junk...
2. http://environment.about.com/od/greenlivingdesign/a/junkmail...