Delta Air Lines, in an attempt to increase revenue, launched a program charging for what it considered to be preferred seats in the coach cabin of all of its flights.
The major problems with the Coach Choice Seats program included but were not limited to the fact that not only were elite Medallion SkyMiles members being charged and subject to the same rules as non-elite passengers for these seats, but some of the middle seats were considered premium seats as well!
Based on feedback from dissatisfied Delta Air Lines SkyMiles members, Delta Air Lines has since rescinded the Coach Choice Seats program for its elite Medallion members but reported still has it in place for other passengers. To its credit, Delta Air Lines does listen to its customers.
For additional details on what many FlyerTalk members say amounted to a poorly-executed program, please read the following threads: