My Liquid Force board is 5.7 kg and the foil in just over 3.8 kg giving a total of 9.5 kg.
For walking from the rigging area to the beach the weight is not a problem. Even for a walk of shame up the beach the weight is not a problem. You just have to make sure it is properly tucked under your arm and balanced.
If I had to do a couple of km walk back I would want to rig some kind of sling or even do a pack down of the foil. I haven't really pursued this because we've been able to get back to the start when the wind drops out, even though fast, light wind, downwind riding is kind of technical on a foil.
In terms of a luxury experience, light weight really matters. It's just so much more pleasant and comfortable if you can pick you your gear and walk effortlessly with it. There already exists a water sport with heavy, expensive gear. It's called windsurfing.
The real attraction of alloy foils is they are generally cheap. When you're learning it is almost certain you are going to bounce your foil off a rock. That would be heart breaking on your $2800 full carbon work or art (closer to $4400 including the board). Not so traumatic on a $1500, second hand alloy kit, including board.
The negatives of alloy in real world use is the mast fills with water, and galvanic corrosion. Both are more a nuisance than a real problem, but a properly made carbon kit suffers from none of those problems. Plugging the mast with silicone had not been a great solution to leakage in my experience.
The other issue is the low aspect wings attached to most alloy foils. They seem to be only good for very slow riding. This is great when you are a learner. Foil face plants (foil bombs) hurt. A lot! I have very little experience of high aspect foils (that will change soon). I am hoping I will be riding much faster with more stability.