I really hate my view on the Circles and Mages - because it sits in this very muddled middle area where I think something like the Circles are needed - including the mandatory-ness of being part of it (at least enough to be trained) - but the way they worked before the Mage-Templar War is immortal, inhumane and, from a practical standpoint, utterly untenable.
Mages needed to be trained - and untrained mages are dangerous, much more vulnerable to demons. If one mage goes rogue, their capacity for destruction is quite high. Templars need to be available to watch mages - but they also can't have the freedom to act that they did before. I think one mistake that was made was having the watchdog of the Templars, the Seekers, be made up entirely of Templars - which means they'll all be pretty sympathetic to the Templar argument, mostly.
You can't have the watchdog too much in sympathy with the ones being watched (though you need a certain amount to allow for nuanced rulings and such).
And of course, there's no reason to pen mages in so utterly in the towers, make then unable to see their families and whatnot - and most of the rest that goes on.
The basic idea of the Circles is sound. The execution by a mage-hating Chantry and badly trained Templars is bullshit