In my opinion they're less effective than they should be because of engine snares.
That is also true. I would like to see snares do much more damage but only cause engine damage at either 33% or 50% health, but that's too big a change to happen in this game. Maybe in a future CoH if one ever comes out. But in order for mediums to stand a chance against heavy tanks I feel like side armor is also necessary to allow for flanking of armor. It's almost impossible to flank a non-casemate tank in the current game simply because there's really nothing to flank.