Glove modifiers very lopsided towards physical?

Heya.

Was such searching trade a bit to look for decent gloves, and noticed the modifiers that can roll on gloves seem to lean heavily in favor of physical / attack builds.

Theres
- attack speed
- mana/life on hit with attacks
- mana/life leech with physical attacks
- add element or phys dmg to attacks
- accuracy
- + level to melee gems

Many modifiers that are only relevant for physical attackers. Yet the other way around, there's no modifiers only valuable to casters. There's attack speed but no cast speed. There's mana/life sustain for physical, but none for spell (except on kill that works for both). You can get +level to melee gems, but nothing for spells or elemental.

Is this imbalance intended or a bug?

+1

for spells any damage type can be leeched as life
but for attacks its limited to physical damage everywhere, why so unfair?