With fees, the network solves certain issues (incentives for miners) but simultaneously causes others (chiefly incentivizing intra-exchange transfers as an alternative to relatively expensive, time consuming and uncertain on-blockchain transfers; also increasing secure and holistic implementation complexity, raising the bar for newcomers thus acting against heterogeneity of commercial exchanges or other automated systems, and thus overall network health). The intra-exchange transfer incentivization is a serious issue as it encourages real world average joe users, who have less capacity to recognize the forfeited value of the public blockchain when requesting their exchange to execute such internal maneuvers (consciously or otherwise). Ultimately fees may decrease heterogeneity in the exchange market and create more central points of vulnerability (regulatory, technical) for the network as a whole. That's just how I see the situation: am I missing something? I wonder, how long until large exchanges perform off-blockchain transfer and allocate mutual credit (eg. via escrow deposit) to facilitate instant, fee-free, off-blockchain clearance for their customers, thus coming full-circle from conventional finance?
