Now I've thought about it more I think that those pushing for very large block sizes really are rather confused as to what they think this will achieve. If you can't reverse your payment (due to say not getting something delivered) then why would any online purchaser prefer to use Bitcoin (and talking about escrows is just silly as people don't use escrows when normally purchasing things with credit cards as they don't need to - you can generally just complain to your credit card provider and the merchant will lose out which is what most consumers prefer).
When people use their card they are essentially using an escrow - Visa or Mastercard etc. Why wont coffeeshops etc just use a bitcoin payment processor like bitpay or coinbase etc? And I don't really see the issue in the buying coffee argument either. If someone sends money for a coffee or whatever else) what are the odds that it either wont confirm or will be a double spend? How would someone even try to double spend in this situation? Personally I don't see the issues here but I'm no tech expert. Bitcoin may need to be tweaked as it grows but i don't think there will be any issues it can't handle or overcome.