Le sigh.
From what I've seen, no. Using Barrier is handy and helpful, but moving around the battlefield, sensible positioning, Guard, Stealth, etc. are now all just as viable builds for avoiding damage. Especially Stealth which I basically never gave any rogues before because it meant less DPS - and if they were low on health then that was what healspam was for.
Moreover, Barrier positioning will likely make it quite hard to spam. While it's easy to drop a Barrier over the whole party at the start of combat due to close grouping at first, as the close combat and ranged characters split up and you manoeuvre your party into different positions, it might become quite difficult to find the optimal 'barrier spot' to cover the majority of the party, forcing you to think before you barrier.
On TOP of that, a number of characters may have various barrier buffing offensive passives on their mages that you may want to take advantage of.
While I think Barrier will be important, I don't worry about spamming it. I'll probably have one person in my party with it, cause it looks handy and I love cheese, but I can envisage perfectly viable builds without it.