will happen on naked bikes - you have air pressure pushing it into your forehead.
Arai, etc do make road helmets. They focus on track and that's where they make their name. If you ride a sports bike then a sports helmet is appropriate due to the riding position. If you ride an upright motorcycle then most of their range is not suitable. For a crash it's not relevant.
Shark do a top of the range hat which comes in two models, one for sports bikes and one for more upright bikes.
As for modification - a small amount of pressure to expedite the normal bedding in is fine. Over time heat and pressure will deform the inner layer of polystyrene anyway and many hats have another small gel layer before this.
Any helmet will push into your head if you're on and upright bike. It's not the helmet, it's the fact that the air is hitting it and pushing it onto your head. Design can do little about this unless it made the front pointy.
Yes there's an element of fashion and buying into a name but the right helmet is the one that fits and is designed for the type of motorcycle you ride - sports, upright, or in between. There are helmets more geared towards track use, but if you're riding a supersport then it's perfectly appropriate for the road.