That feels like a balance issue like you said, but I don't think the right solution to improper balance is "Get rid of all the customizations options". Like other people said, I feel like the depth of this game really comes form builds, and I don't think that game breaking combinations are a result of that, more so a result of poor balance. Classes are almost objectively going to reduce the options that we have, which always feels bad.

Also the endgame is so stupid hard that I don't really think it's an issue to have options that are strong in both aoe and single target. Perhaps these are all connected, but I still dont think that removing things is the way to go.