Any magical limitations in most of Thedas, especially the 'South' or 'South Influenced' (Ferelden, Orlais, Nevarra?, Anderfels?, Free Marches, etc?), may be considered an effect of a society that limits magical exposure and education. This era may have some particularly newer styles, techniques, discoveries about magic (and they may have come as a result of the magical direction of this Chantry era), but this is a convenient setup for Bioware to do all sorts of 'new' things about magic in the future.
For example, there is the opening for staves to only be one among many different weapons for mages, or even one among many styles (may be unarmed, use objects not as clear weaponry). Staves are just the most commonly understood useful weapon to channel the magic of magical people.
Tevinter, present and ancient, may have used staves, but these staves may have had more metal involved and have a more clearly physically offensive use. The ancient elves may have used objects to channel power, and perhaps objects with length like staves have, but there's nothing that keeps them being staves. Current Thedas (until more recent events) has been a world restricted in magic compared to its past/potential, and so we have a less magical population needing challenging objects, but using less offensively oriented objects. The Circles only break out the mages for war when very necessary - most often for selective recruitment for the Wardens. However, Tevinter is a (relative) magical holdout that may have more style than the south, and there are hedge mages and it seems the Qunari have select times that they unleash their mages on enemies in a more brutal fashion that doesn't really need staves.
If we're going to Tevinter in DA4, I expect significant expansion of magical lore. Specifically 'magic' - not just elves, mage culture, magical politics, the Fade realm. We ought to be diving deep into what magic means on Thedas, more than any previous game offered. DAO set up the world, DA2 showed us there's some more variety to its magic, and DAI unlocked the door to bigger and more varied interpretations on magic, but DA4 in Tevinter should be all about this stuff. Some players won't like this, but I'd assure them that there was always going to be more magic story in a Tevinter game, while games after it may ease up again and go on other emphasis. Its just Magic = Tevinter. There's a lot to learn about higher schools of magic (and even secrets or discoveries about 'mainstream' known schools) that the South simply mostly wouldn't explore unless the society was collectively pressed to do so. Obviously Tevinter won't be so advanced and powerful that the tales of it falling within and without would be unbelievable, but even today it resists the Qunari, has kept itself from utterly collapsing politically, has defenses that most of the rest of the present would should be envious of, and all through this, it presents an image and perhaps reality of a realm that would still repel the collective warfare of all of the Chantry/southern realms, albeit perhaps barely now. They gots good stuff.