The NPC drop rates don't need to be nerfed to the ground, but the 0.2% chance cards could do with a bump. Personally I feel 1% lowest is a fair droprate for 5 stars. Similar to how you've done Omega 120 times, some of us face Hab 700 times without a drop. Both are excessive.
4 stars definitely need a use. 1 per deck perhaps, similar to 5 star.
It's amusing how outdated the tournament rewards are compared to Verminion now. For a 10th place TT finish I get 30k mgp and 3 Lahabrea cards, for losing 1 Verminion game I get 80k mgp.