The requirement was removed for various reason, the main ones being that they were the bottle neck of matches starting, when you had enough players by count to be able to initiate them otherwise.
The issue behind why it's being asked for is for "fairness" that each side have a Cleric, but forcing a Cleric to be on either side still doesn't guarantee that fairness is going to occur. The Cleric could be a battle build, or some other variant without the "necessary buff" to be identified as a support build.
If you want to have a Cleric on your team, group one, call in friends, clannies or recruit off the street, however you do it, you have the power to control a bit of who's on your team so try to make good use of it!
As for the reason why Clerics are so highly coveted, is because they have the one thing no other class has, healing. No other class has that ability at current, and it is something we're working on, so there is less reliance from Clerics as a whole for the role of support. We're working on designs and plans to help spread some of that responsibility in unique ways so they are less needed by name, but rather they can become an option for support for many who would care to take that role of support, but not take the time to play or create a support Cleric.
Through much of the efforts of skill and class balances, game play has shown to be evening out greatly over time, however as mentioned that aspect of providing healing for support is still locked down to one class, which places a high importance on that class, currently. Look for the coming updates as we begin to put effort behind this issue.