U.S. platoons have several SAWs as well, I'm missing an equivalent in your description. The firepower is too small without anything in between GPMG and AR.

Long-range rifleman are a waste. Make them snipers, sniper training is cheap as they're on active duty anyways.

A 20+ % leader ratio is very useful for force growth/mobilization. It enables the force to quickly double or even triple its size.
Small unit leader survivability is often lower than common infantryman survivability. The percentage of leaders would drop quickly in a high intensity conflict anyway.
Plus: You'll find out about a lot of unsuitable leaders once a conflict goes hot.