1) You are missing that miners are interested in fees. They have a right to include/exclude any transaction.

2) You are missing that it is almost impossible to upgrade relay policy on thousands of nodes.

BTW. This is funny test.
Miners just raised the minimum fee, leaving a lot of unconfirmed transactions and screaming users.
Blocks are not filled.
Right now mempool on https://tradeblock.com/bitcoin/ is 12mb (note: transactions with a fee less than 5 satoshi per byte are ignored)

https://en.wikipedia.org/wiki/Tragedy_of_the_commons

Edit:
3) Since the start of this stress test the price on exchanges rized up. Everybody likes it 
Are you sure that you really want to fix this issue? A lot of people would vote against