The low brow height is fairly common in many RS helmets, and there are some on-screen helmets that have it. But I too prefer a brow height somewhat higher as I think it is more typical of most on-screen stunt helmets. But all things considered, I agree better to leave it as it is. And as you read through this post, you'll probably agree.
The brow height and shape is determined by a combination the points of assembly of the faceplate (front half) and cap&back (back half) secured by the screws in the ears and the trim of the cap&back plastic to which the brow trim is attached.
There are a number of ways to raise the brow height. Some easy some not so easy. And shortcut methods which might stress the plastic and the risk cracking the plastic and/or the paint.
A not so easy method but probably the best from a purist perspective is to disassemble the helmet by removing all trim and screws and adjust the positioning between front and back. Brow height can be raised by either increasing the vertical separation between them or by tilting the back half backwards or a combination. A tilt will induce an upward curve in the brow at the center. The downside of this reassembly method is you need to drill new holes perhaps not in the ears but certainly in the helmet, and the ear fit will change and may induce more gaps and/or require ear trimming.
Another thing you could do is trim the cap&back at the front higher where the brow attaches. I'd be hesitant to do that though because it looks like it's already trimmed high enough. And in any of these modifications you need to be careful that a higher brow height doesn't result in it extending forward too far in front of the top of the faceplate.
The shortcut method that I have used on several of my helmets (ABS Anovos, ABS SDS Battle Spec, and HDPE Dan Laws) is to simply increase the separation between the front and back from the inside at the top and install a brace between them to secure that separation. I use molded instamorph as the brace, once it's hardened then added a strip of industrial strength velcro to it and to both front and back helmet halves at the seam. This allows me to adjust the brow height. The downside of this method is it can induce stresses and cause cracks in the plastic or paint. A particular stress point is at the top of the ear so I loosen that top screw and often all three screws just to be sure. And yes I have caused a small 1cm crack in one helmet doing this (to the battle spec, no great loss) in the cap&back above the left ear. The ear screw was pretty tight at the time it cracked, and I've since repaired it with some ABS paste (mixed from scrap ABS and acetone).
Here are some pics of my white HDPE Dan Laws helmet with this shortcut modification.
