I honestly don't see how this is any different from XI's practice of muling (buying character slots to use as storage and sometimes played to repeat quests for rewards). Paying for another retainer just adds 175 more storage slots and, with the Venture system, the opportunity to gather materials through quests that likely prevents access to said retainer for the duration... wait, this sounds familiar. Ah, SWTOR's companions! Remember that SWTOR started as a subscription MMO, too. Also remember that there was DLC that added more companions, if I recall the DLC wasn't free.

That aside, even if you don't buy more retainers, the ones you already have can still do Ventures free of charge so... I don't see what the fuss is about. So someone buys another retainer, the benefit is incidental at best.