might just be the way your body is,,, i much prefer inclines, i will never flat bench again, for my structure it just kills my shoulders, i wish i never performed a single set of them to be totally honest
one things for sure, you dont need flat benches to build a good chest, incline bb or db, flat or slight decline db presses, db flys,,,
anyone who says otherwise is a brainwashed powerlifter or stuck in the pumping iron days