As (nearly) all talents have diminishing returns, they mostly feel unnecessary even before reaching the current level cap, at least for me. Improving any dps talent from, let's say, 30 to 31, adds so little overall dps that it can hardly be noticed. I would prefer to add more talents instead of more levels, as they contribute both divercity and long-time incentives. Maybe a tier 4 talent row, accessible once you hit something between 900 and 1000 on any campaign. :)