With the release of the new "Demacian Heart", a lot of people are saying that Demacia has become basic in its relationship towards mages. I don't believe that is at all for a host of reasons, but I also understand why people feel that way.
In the majority of the color stories we have, Demacia seems vehemently against mages and magic for almost inexplicable reasons. However, we have only seen Demacia from the eyes of the royalty an those close to it considering most Demacian champions in League so far are rather high ranking. And this makes perfect sense. Demacia is built on anti-magic, physically and culturally. And in "Demacian Heart" we see that magic can be used to tend crops in the worst of conditions. This could drastically disrupt the balance of power in Demacia. Mages could grow more crops for longer in the off-season. That alone would give them an advantage over normal farmers that they would easily be able to push others out of the market. Over time, mages would have the money and resources to push out the ideals of nobility with money alone. Mageseekers, to me, seem to be a creation by the nobility to maintain this status quo and keep themselves in power.
"Demacian Heart" also showed us as you venture away from the major cities, where poverty is common, anti-magic sentiment is far less common. Very much like Zaun, poverty and sickness force this people to use whatever means possible to survive. But if the precedent is set to allow people to use magic for crops, the nobility feels it would could end with magic be used for other goals. To me this makes J4, Demacia's heir apparent, accepting Shyvana into Demacia a **VERY** big deal and could lead to some great story telling in the future.
TL;DR "Demacian Heart" gave us insight into why Demacian nobility feels so strongly against mages and that not everyone in Demacia is behind this.
I hope this opens up more discussion into the Demacian trains of the thought and the release of the chained champion will hopefully shed more light on my points.