Greetings,
IMO Talent trees can be utilized well if there is a clear difference in purpose. For example, a tree that heals and a tree that tanks. Both can be superior depending on what you want to do (with minor branches of the tree being more of a preference and not changing output substantially).
Talent trees become broken when you have a pure class (pure dps or pure healer) that have multiple trees to do the same thing, just in a different way. Thats when optimization and balance becomes a road block.