Exploit - No i dont think of it as 1, as you really need to find someone willing to stay there for the long periods of time restarting the quest.
Brilliant marketing ploy - I think so. You look at this from a business perspective, its a mob grind that you get in all mmo's, but, people are buying cartel coins, to buy xp boosters to level a tiny bit faster, and in the end, for those without 50s are getting 50s which means, more people wanting to sign up for makeb (double the money with half the effort)
Plus on an awesome note, i get to farm the squishy recruit geared fresh 50s in WZ's, so the legacy gearing allows me to gear my fresh 50s off thier lazy butts.