Wouldn't be the first time a game included a rule-set that was dangerous, potentially game-breaking and inflammatory on said game's forums, not to mention ill-defined.
No matter what, everyone has to at least agree that it's not very well laid out in the book- or we wouldn't be here... and both sides have had fair points that prove their case. Believe it or not, both sides can be right.
Evocation's a bit of blunt instrument for something as complex as the mind... but if mental veils are possible, blunt instrument ought to be good enough for just direct damage.
The books do at least indirectly reference mental effects through spirit... but they hardly come close to giving it the coverage they deserve.
For me, I'm willing to allow it on basis of symmetry alone. Physical/Social/Mental stress and consequences operate near identically- and their conflicts are as close to identical as the game mechanics will let them get (things like zones/borders/etc can get hinky, but otherwise identical)... so there's very little reason why the parallel shouldn't continue into magic, given the right storytelling & descriptions.
If the game failed to include parallel effects to Toughness & Recovery, that's more likely an oversight than an indictment against mental attacks.
Likewise for power balance issues vs non-humans.
And me, I'd rather fix that oversight than rule out what caused it.... for lack of a better way to put it- surgery is always preferable to euthanasia.
So, if I can redirect the thread... what fixes would make the idea of direct mental damage acceptable to everyone?