However we can raise the Blocksize up to a certain level. What is speaking against an increase to 2 or 4MB and then continue with an increase which grows equally as technological progress?
2 or 4 MB would not mean much in terms of increased usage, you need at least one order of magnitude to make a meaningful difference, going from 1-10% of Starbucks' tx rate to 4-40% would still look just quite inadequate.
That said the current challenge is more propagation times and the risk of orphans.
Even with the "stress test", we never went above 80% of fill rate, and this time it's much less (60-70%). It just does not make economical sense for miners to fill blocks and risk getting orphaned because their block propagated too slowly.
Outside of stress test, blocks are at 30-50% fill since early january, indicating either a lack of demand... or a miner soft limit wrt propagation.
.... I missed out most of day 2, but I am catching up as we speak. 
