I think I can boil my core argument down into a few basic premises (evolved a bit with this discussion):
1. The whole point of Litecoin as it currently stands, is to bet on Bitcoin weakness but presumed Litecoin strength: either on the perceived or probable outcome that one day SHA256 won't be good enough to keep securing Bitcoin, but that scrypt and its current parameters somehow will withstand whatever befalls SHA256.
I think it's merit need not be so "us vs them". If what we're really interested in is a secure cryptocurrency why not develop several in tandem so that all of the eggs aren't in one basket? As bitcoin deals with scaling up, it might be served by having other sister currencies for exactly the other reasons you list, Mike. More of a crypto-economy with several elements which might each contribute to a larger stability.