I agree with OP. Suppression needs to be enhanced for the sake of realism. As of now firefights in this game feel a lot like in CS:GO or COD (meaning very short). Last time I checked this game was advertised as a tactical shooter and IMHO suppressive fire is a vital tactical area denial element. Similar to gunship run or chemical mortar strike etc. which don't only serve to kill enemies, but more importantly to force them to keep their heads down while your team can advance on an objective or simply get a better firing position.
Machine gun fire doesn't scare most players as it should. Most of the time if the gunner misses the enemy it only gives away his position and the person on the receiving end just fires back with no problem.
I absolutely love the realistic gunplay in this game, however some aspects make it feel like Counter-strike/Call of duty on steroides.
A very good example of suppression effect is done in Battlefield 2 mod Project reality, where while under fire your screen gets blurred to the point you can't return fire effectively, resulting in longer and more intense firefights.