I think walls are underused for many reasons, one being because they are a double edged sword - you can block off areas but you also block yourself off. To make them more user-friendly, is it possible to allow friendly units free passage through your own (or team) walls? The wall model is well suited for this and would not look strange. It would simply be your own units going through a "smart" wall system that blocks enemy and friendly fire but allows friendly units to phase through the energy part. I just want to make walls more viable.
That too. See it is not hard to get great ideas for the walls. If someone were really motivated a new defensive structure called a "gate" could be created, which would be a special wall entirely dedicated to opening and closing. I literally see no wall play whatsoever in recorded matches these days.
Walls are already very powerful. They are used more to block shots than to block movement. I see them all the time.
When do you see them, though? When I see them they are most often used by noobs who want to turtle. As we all know, turtling is not viable. When I spectate high rank 1v1's and even normal party matches, I never see them in the former and rarely in the latter. They have high health which makes them useful to buff T1 turrets I guess..., but late game they are demolished easily by most T2 crap, which can shoot above walls most of the time anyways.
Often, you'll see players putting just a few walls (1-3) in front of a turret to keep it alive for longer. This really helps against t1 units and also slammers.
Another pretty common use of walls is to set up a quick wall with a Mend and sit Slammers behind it. This can shred pushes and is particularly good in maps with chokes.