If you double the blocksize, you also double the fees miners get paid without increasing the rate at all!
This might increase the cost of mining by some tiny fraction but nowhere near 100%. So let's be generous and say 2MB blocks will cost miners 110% of 1 MB Blocks.
So how about this calculation:
scenario A: 12.5BTCblockreward+3BTCxactionfees=15.5 BTCminerreward
scenario B: (12.5BTCblockreward+6BTCxactionfees)/1.1=16.818BTCminerreward
And that doesn't even factor in the very likely probability that BTC exchange rate will go up significantly due to the added utility.
So why do miners object? Could it be that they will get no reward at all because they are mining over a slow internet connection (through TOR or behind the Great Firewall) that means they cannot compete with miners with faster connections?
All the other objections are just to obscure this one. The real one. Forget the decentralization argument. Forget the "any hard fork is too radical" rationalization. These are not honest people and they are taking wealth, not making wealth.
Maybe cause they want to show solidarity and are hoping for an organic growth of the core without intensifying the fighting and splitting in pro/against camps
imagine what would that do to a price
Maybe also there is a sense that "if it's not broke, then why fix it?"
It IS broken. There was a five year exponential trend that was decisively broken, despite wider adoption, dozens of new use cases, and millions in VC investments. Why? Gavin, Garzik, and Hearn are experts who know what they are talking about. I don't know code as well as them, but I know economics. It's the science of incentives. All you have to do to get a project to work is to get the incentives right, but if you get them wrong, nothing else matters.
You can have cancer for a long time before it kills you. You can have it for a long time before you even notice. Some problems don't go away when you ignore them. Some problems get worse. If your doctor tells you you have cancer, it may be wise to get a second opinion, but it's extremely dangerous to ignore him, particularly if there are noticeable symptoms.
Scale or die.