it's not so much "cost" as time/workload ... the finer the detail, especially with fluids, the longer the time/workload/rendering process -- the goal is to have at least 1 animation released per month (as it seems), and super attention to detail will always drag something out (not that ARG "doesn't" do fine-animation such as tongue/nipple/kiss etc)
the ARG brand has been releasing videos for around 7 years, with menu different types/styles/fetishes -- not sure i agree with your animation assessment, but all the same, the current animations are part of the ABW series, which follow a different ... "archetype" than the AMML series, and with a plethora of "new" characters being released lately, of course there will be a focus on the penetration, i mean, Chix with Dix gotta do, you know?
at it's simplest, could just be a phase of focusing on penetration; in example, a few years back there was a lot of focus on fluid simulation with cumshots and belly inflation (including a rare video with a pregnant Bella) ; scenes like that aren't as often anymore, creative license, if you will
TL;DR : i can assure you that if the animation feels stale/redundant, it really isn't, and if you disagree, all i can suggest if finding a different animator for your kinks/fetishes/etc