Sorry, I miscommunicated. I'm sold on the utility of 81mm & 120mm dedicated AFV.
I was referring to the 60mm mortars the French & others installed on some of their light AFV: South Africans & Rhodesians used them for example. One of my rellies obtained a 60mm & rounds from US sources and mounted it on top of his MBT and used it for many of the reasons you highlighted: smoke/WP, illume & the odd HE. Filled the gap between his M79 & the long gun.
It occurred to me if much of your forces are on light AFV/protected vehicles, might not a bracket on the deck for inf to slip a 60mm onto be worthwhile?
If I'm not mistaken, that's why the Israeli's have an internal 60mm mortar on the Merkava MBT in addition to M2 and 2x 7.62mm GPMGs.