It was actually changed to be easier, and to match todays International Airport Standards. It hasn't just changed from a numbered system to alphabetical, but it also has a specific colour for every Concourse.

When checking in you cant go wrong because if your flying EK you can only check in at Terminal 3, and Concourse A/B, and C are all interconnected.

If your flying FlyDubai, or the lower budget airlines you go to Terminal 2 which is at the other side, it's also Concourse F, and which means we can expect a Concourse E in the future which will most likely be linked with Terminal 2.

If your flying with all the other major airlines you will check into Terminal 1 which is linked to Concourse C. In the future Terminal 1/Concourse C will have an APM linking it to Concourse D which has already started its building process, and should be finished 2015.

Also come 2015 if your flying EK you will be able to check into Terminal 1, and 3 since EK will take over Concourse C, and all the majors will be transfered to Concourse D.