Personally, I always thought - and still think - that the division of units into "Battlefield roles" in most cases is artificial and far-fetched. And thus slapping the ObjSec rule onto all Troops indiscriminately feels a questionable decision to me.
In fact, there does exist an opportunity to raise 40k to a whole new level of balance by introducing a similar rule with just one important difference: instead of giving ObjSec rule to Troops, it should've been given to all Infantry. And also, ObjSec rule itself is silly tbh. A much more appropriate way to implement the same idea is what we had in 5th: make it so that only Infantry can control objectives, and other unit types can only contest them.
IMO, a rule like this would fundamentally change the appearance of 40k armies, shifting them towards having a strong infantry core, and thus making them simultaneously perform in more balanced way and look more like proper armies.