The Russians built light, short ranged fighters not suitable to heavy multi-role bomb loads.
The British did increase the loads their fighters carried. The Spit I and Hurri I carried no bombs, the Spit IXe and XVIe carried 1000lbs, the Typhoon carried 2,000lbs or 8-16 rockets, the Tempest carried 2,000lbs, the Mosquito VI carried 2,000lbs or eight rockets and 1,000lbs.