The wheeled mules I'm talking about are not noisy though. From the article:
> Although quadruped robots like BigDog from Boston Dynamics is no longer in the running (it turned out to be a bit too noisy), there are numerous wheeled alternatives.
Regarding your second point the article seems to come to a different conclusion:
> A British army study, called Project Payne, found that far too much of what is carried is “just in case” and that the amount of ammunition carried by troops is excessive.
But it does fix the problem of it becoming an attractive target for the enemy. If the mule carries special weaponry, taking it out is attractive to the enemy. If it only carries stuff that the squad isn't going to need in the current engagement, there's no reason for the enemy to focus on it.
Noise is a different issue of course, but the article mentions it only for the walking "big dog" mules, not for wheeled ones. And if the mule only carries stuff that's not immediately essential, it doesn't have to stay close to the squad. If it can follow them autonomously (which is probably a requirement anyway), it could trail them at some distance.
2. There aren't many truly "It's OK to lose it" items, as they'd all have been lost by overburdened soldiers already.