The rationale is off too. There will be girl trousers and boy trousers. So they wont be gender neutral unless they are all made to wear the same trousers.
The reason that uniforms tend to be skirts for girls is because womans waists hips, bottoms legs come in all shapes and sizes and are much harder to fit than men.
This is why girls/womans cheap trousers tend to have a stretch in the fabric as the cut becomes less important. Yoga pants fit all as are stretchy.
men tend to have a more up down straight shape.
If you are in the size 12 range you may have noticed that the sizing is all over as people shapes tend to deviate a lot at this size. fat is deposited on the hips for some on the bum for others and the waist.
I say trousers and nice kilt option for all.