I've always found that the thing with Maxims was that they were cost effective to reinforce. Point is, they are/were cheaper to reinforce than conscripts, which made hard to justify the 'cheap, expendable' conscripts with merge.
Also, maxim spam was effective against OKW because conscripts are just awful against sturms and volks. Penal battalions more often than not are just asking to be rolled by Luchs. I wager if the sniper team or scout car had been swapped with the maxim in T1 and T2 there would not have been the kind of maxim spam we'd been seeing. (Essentially maxim starts didn't require [back]teching for ZiS.)
The issue with maxims has always been an issue of Soviet teching and doctrine design than with the unit itself. The maxim can certainly be made to be less and less cost effective, but that's technically reducing an already limited selection of viable strategies.
Hopefully the patch and the beta preview will help clarify.
