DND_Reborn
The High Aldwin
Others have suggested more atunement slots in general, but casters have to use them for higher level spell slots and such.Adding in player facing magic item selection would help with power/versatility, and could actually balance with attunement. Non-casters get unlimited attunement, minor casters get 4, 9 level casters get the current 3. Have attunement for all permanent items.
By removing this from 5E, they further contributed to the "mother may I" issue with being a non-caster.