[PlasmaKrab]

Looks like the Arkan-based 115mm missile is heavier, I think the previous versions were saboted 100mm missiles.
Anyway there are at least two or three versions of the missiles for each launcher (T-55, T-62, BMP-3, MT-12...), wouldn't that clog the OOBs too much?

As to why they don't develop top-attack missiles, maybe for cost reasons? AFAIK the EFP warhead requires extremely accurate engineering, rare materials and very smart seekers. Apart from the US missiles and mines, I think only Bofors manufactures them in large quantities.