Advice between Pure elemental or using physical conversion

Good Day All.

I need some advice on this build I am using. I have planned the build to get 41% reduced reserve out of the tree to run my auras.
I plan to run LA + Blackgleam to convert a bunch of damage from physical to elemental and then abuse stacking the more Modifiers. Namely Weapon Elemental Damage + Projectile Physical damage and then using the added mods of Added Fire Damage and Hatred aura.
If my maths is right I should at some point be able to run 3 aura and would added anger and wrath to this.(Though I stand under correction)

What I don't understand is that I don't see anyone else doing this. Most of the elemental builds I see completely skip physical damage entirely and focus on Wrath/Anger/Added Cold/Added Lightning

Is the Wrath/Anger/Added Cold/Added Lightning the better route and using a bow with elemental damage better than my plan?

PS: As of right now I haven't taken any damage nodes. because I'm not sure if crit or ele damage would be better.