Linuld, really... you are asking the same questions that have been answered like a thousand times, and making arguments that have been countered a thousand times...
I will only comment on some of them:
On top... you know that the current blocks are not even filled full. They only are full when these spammers act. And there is no reason to assume that suddenly, with 8 Megabyte Blocks, these blocks will be full. Where should all these transactions come from?
There's a perfect reason to assume that blocks are suddenly 8Mb -- if there's a specific attack vector linked to full 8Mb blocks, it will be used. It's not that expensive, especially when fees are gravitating towards infignificant amounts due to big blocks.
8 Megabytes per 10 Minutes and you think we will get in problems with that? What kind of internet connection do you have in order to fear that?
A decentralized network robustness depends not on an average throughput, but on the throughput of bottlenecks, namely network bottlenecks (China-ROW, e.g.), CPU bottlenecks and others.
CPU bottlenecks are currently being worked on by core devs.
Sure. And will you pay that? You realize the cost of the recent spam attacks? And those were only some KB. You speak about filling up a lot MB with spam. I wonder if you will find someone who will do the spamming.
Do you realize that yeaterday's attack created more than 35Mb transaction backlog -- enough to fill more than four 8Mb blocks.
The previous attack had much larger backlog.
And of course i referred to the natural adoption of bitcoin that will fill the blocks. Spamming won't happen since it does not make sense then anymore in any way for the spammer.
"Sense"? What's the sense for an attacker currently? Do you realize that with this
natural adoption even 8Mb blocks will get full at some point, and the closer they get to 8Mb, the less costly is a spam attack.
We can't solve the spam attack by allowing for more bloating, we can fight it only with fees, which are bound to go towards zero if we keep increasing blocksize limit beyond demand.