Unlimited warzones, unlimited flashpoints, unlimited ops?
I believe those are all perks that subscribers get. There are others too, but that is what you are paying for. Im pretty sure you can unsub and purchase the expansion and be considered a "preferred" player.
I cant answer why you are subscribing, that is up to you.
I have to reply to whoever wrote this ... let me see all that was there since i started playing and paying for this game how is this some kind of perk ... and i pay six monthly subs in advance and paid for this expansion in advance they wont give me my money back and thats part of the problem they dont give a damn now they have it