I'm not saying they missed the mark with that design, just that internally theres way too much overlap. You look at hunters as an example, one whole subclass built around your melee/survivability. Another subclass built around gunplay (minus blade barrage). And another built around locking down your enemies while supporting your allies (excluding spectral). Titans have striker that grants buffs and damage for punching targets. Sentinel punches enemies and uses their effects to support your allies. Sunbreaker uses your abilities to proc buffs which lean heavily towards the melee. For warlocks, I think the void rework is where their diversity will set in because besides devour they are VERY similar. For arc though, you have a tree focused on chaining lightning for area control. A skill tree focused on accelerating your super regeneration and uptime. And a skill tree focused on supporting your allies with rifts and arc souls. I already went over dawnblade. Even within each subclass on warlocks, they play differently with similar designs. Titans just get in your face for buffs and healing 70% of the time. Still good obviously, but nothing that stands out amongst themselves.