I can understand where concerns like that would come from, and especially since these new systems still can't be experienced for the players yet. But I believe everything has been thoughtfully designed to avoid such issues.
Each Arcana has it's own strengths and weaknesses and I imagine most players will be changing up their loadout to suit whatever point of the story they are currently at, especially in new game plus when they have the full roster open to them right from the start. But of course there's only so much I can ever really get across with words alone. For now all I can ask is that you trust me and wait for the demo to experience it yourself. Though even then the demo will likely only include the first 2 classes. Still it should be enough to sell the idea I think.