This is the intent with faster patches as well - you now have more content than before (you currently have 4 raids !!) but you are simply saying 'i dont wanna do old raids because they are old'.
In that case, they could have released 5.2 raids in September 2013 .... But all the people who HAVE already clearled content would be pissed.
This is the best solution : people can catch up, others can progress.
Before, you'd have the people who cleared tghe content just stop playing for 5 months until the new raid came out ...