Well, since I'm mostly on the sideline of the XT issue (because I don't consider max block a significant enough economic factor), I'll add that the protocol literalists have spun a respectable number of fabricated crisis narratives themselves (uncontrollable spam, lack of LT mining reward, etc.). IMO, it replaces one potential pitfall (mostly technical) with another one (mostly psychological): turning the Blockchain into a pure high-stake clearing network before it had a chance to establish itself as a useful, reliable tool for smaller transactions is not without risk either.
For the spam justification of the limit you have to ask Satoshi.
Spam attacks have also been proven a very real threat.
Okrent's law: "The pursuit of balance can create imbalance because sometimes something is true"
https://en.wikipedia.org/wiki/Argument_to_moderation
Does he even realize what he is saying 
right, sidechains with actual locked Bitcoins as backing are Ripple