Addendum:

Please do not interpret - as many have - my points as advocating against
letting a fee market ever develop(!).

Fees are useful against DoS, increasing cost of attack etc.  Further,
continuing the artificially-low fee policy ad infinitum is unsustainable
and constitutes a moral hazard.

Examine from the user's point of view.  If you want to develop a fee
market, think it through in the context of user expectation/experience -
which translates to how software is written and users behave, the context
of market disruption, and the context of further block size increases.

Transition to a new economic policy should be planned.  It should give
users and markets time to adjust.

It is grossly irresponsible to simply drop users into a new economic policy
with no warning and no preparation.