Surely every genre of bike deserves to be as light as possible - budget allowing. IMHO weight always matters. All mountain bikes do go up as well as down you know
The only thing that matters is whether the bike feels right to you when you ride it. I have ridden bikes that were light on paper but felt sluggish, and heavy ones that felt great. I don't know what my bike weighs, and nor do any of the people I ride with - it just seems an odd thing to obsess over when buying this type of bike.
The amount of difference between a 'heavy' and a 'light' all mountain bike is a fraction of a stone of your own body weight anyway.
And yeah apart from the Enduro are any of these bikes 6" travel?