The odd shapes are one of the areas of innovation.
Because the FIA limited the placement and size of aerodynamic fins (i.e. spoilers and front lips), the engineers started using other aerodynamic innovations to increase downforce. One of the most interesting things to come out of F1 cars, from an aerospace engineering perspective, is the use of eddies and other circular air motions underneath the vehicle to drop the pressure (and create a corresponding downforce).
Just because the rules stop innovation on something like engine tech doesn't mean innovation stops; it just means it moves to optimizing other pieces of tech.
Because the FIA limited the placement and size of aerodynamic fins (i.e. spoilers and front lips), the engineers started using other aerodynamic innovations to increase downforce. One of the most interesting things to come out of F1 cars, from an aerospace engineering perspective, is the use of eddies and other circular air motions underneath the vehicle to drop the pressure (and create a corresponding downforce).
Just because the rules stop innovation on something like engine tech doesn't mean innovation stops; it just means it moves to optimizing other pieces of tech.