Cover should cap at 3, not 2. My reasoning:
- It will give units with low profile a use for their ability to use cover a bonus in heavy terrain.
- It will give units with suppression tokens a bonus in heavy cover.
- It will make it harder to shift units in cover.
- Bigger/heavier units will be more useful, as smaller units will struggle to get past the cover.
It makes sense thematically. Because units that are good at using cover would have a greater bonus in heavy, not just light cover. The same goes for pinned (suppressed) units.
Cover to me, feels like it doesn't quite have a strong enough bonus in some situations. Faster/beefier units seem to ignore it as much as possible, focusing instead on total line of sight blocking terrain.