First of all, from the steem whitepaper it doesnt seem that by declining payout you "BURN" steem. It just remains in the reward pool. Theres a difference imo.
Promotion should never be free, or you get the worse of the worse!
This is point one we try to make when dealing with bidbots.
Honestly, who is anyone to think they deserve a free spot on trending?
This is the second point. Its a trending page for stuff to trend by proof of brain, by a large number of people deciding its "hot shit".
If the bot delegators and bots dont care what the content is or dont even look what posts are that use their service, regardless of them blacklisting the worst offenders, even those that dont create absolute shit content, their content wasnt "picked", "chosen", "evaluated as being something that wants to be seen" by any larger group of people.
It was just decided by the guy that has the money to pay for that spot and that action is quite detrimental to the platform.
If they for example burn the Steem to trend, that would be a positive action as a counter balance to them taking the trending position. That doesnt happen.
Paying the front end to place on top would be positive since its the front ends choice to place them there and that goes towards more development, employee pay and it doesnt create unnecessary inflation.
You can't put certain people on pedestals and say it's ok for them to use bid bots for free trending space but not others, that leads to Old Steem quicker than an elevator to hell.
Exactly. Thats what i mentioned in my last post with the "fyrst example". You cant let people wiggle themselves out as a "exception" just because they promised to do something, even the smallest insignificant thing. He so easily manipulated people on steemchat the other day. He got so confident that he stacked bot votes to the top of the trending page 2 times and then Whatsup, that actually talked to him on Steemchat upvoted him.
People will promise anything for the rhetoric to soften.
We cant let that happen.
These two users declined payouts, then used bid bots to reach the top of the trending page.
This is a much better option, but still not ideal. Forcing declined payouts is positive in the sense that it gives our trending page "ad space value". Thats a huge benefit. Before, our ad space was worthless.
Still, the tokens arent burned (like you said here) which would be the best option since it would provide Steem a sink which it does not have and desperately needs and would work to reduce inflation. By declining payout the steem just remains in the reward pool for others to use.
This opens an opportunity for front ends and ill ping 
That creates a business for front ends and makes them sustainable, profitable, much more so then bidbots that only take a small 5%-10%-15% (or what ever it is) cut and the rest going to delegators.
The front end could take 100% of the promotion payment, which in turn avoids unnecessary inflation, which could potentially lead to higher quality front ends we so desperately need.
RE: To Bid Bot Or Not To Bid Bot, That Is The Question