Because of the culture it engenders in the company that they can continuously peddle crud with no impact on revenue. The cost of fixing issues that severely impact player satisfaction is outweighed by the loss of revenue the time needed to fix those issues would cause if the relentless treadmill of events was stopped long enough to fix them. Simply because people throw money at them like drunks in a saloon so they can keep drinking the watered down swill they serve with their faction "buddies", that, ironically, they would never go with for a real drink anywhere, anytime.