I agree with Zura that Mages shouldn't get Root: they're meant to be an almost melee-like class. But, at the same time, when a melee gets an extra unexpected mob on them, they can take hits and ignore it for awhile. Caster's can't, which is one reason they all get Root ... except Mages.
What Mages need is an Enchanter animation-like pet spell line that stacks with their regular pet and has a quick (Root-like 2 second) cast time. It would do almost no damage but have a strong taunt, and while you couldn't control it, it would attack whatever mob you have targeted when you cast it.
With that, a traveling Mage who agros a mob could summon their quick cast pet, and use it (like Root) to delay the mob until they run out of range. Similarly, a Mage who gets an add while pulling could use the pet as CC. It might not be as good as a mez, or even a Root (although it would be slightly better against mobs that can't be rooted) ... but it would balance the class by giving them options every other caster has, in a way that's still true to the class.
P.S.
https://wiki.project1999.com/Dyzil%27s_Deafening_Decoy seems like maybe it was meant for this ... but it doesn't stack, it's not a spell line (just a single high level spell), and it's useless because of the 8 second cast time (Rot is only 2 seconds ... plus Root only costs 40 mana vs. the Decoy's 350).