It will help to replace witnesses and decentralize the coin.
Market does not 'decide'. Market does not do any decision.
What fee in $ would you accept? And how do you know it is not lower than market 'decide'
Market decides the GBYTE price and since transaction cost is roughly between 500-600 bytes, the cost in any other currency can be calculated. If people don't want to buy GBYTE when it is too high then somebody else will sell it for lower and vice-versa. How else do you think markets work?