I still think the PHB has too many spells and the DMG has too many items hogging up pages.
Like the PHB wizard spell list should go old school.
8 spells per level except 0th, 1st, 2nd, and 3rd. 1 spell for each school past 3rd. That's it.
Everyone else gets only ~5-6 spells per level.
Cut it down. Cut it down. Shove those extra items spells in its own book.
So one thing that can help to pare down spells is go whole hog with the whole "cast at higher levels" thing and combine spells, especially damaging spells. With a 1st-level slot, it functions like
burning hands (small amount of damage in a small area)
. With a 2nd-level slot, it functions like
Aganazzer's scorcher (moderate damage, moderate area)
. With a 3rd-level slot, it functions like
fireball (large damage, large area)
. And so on. You can do this with non-damaging spells as well. With a first-level slot, you have a visual-only illusion. With a second-level slot, it becomes audio/visual. Etc. First level healing restores some health by touch, or less health at range. Higher level lets you cure diseases or get rid of conditions.
You'd cut the number of spells by at least a third. And let's face it, it's unlikely that 6e will go back to making wizards really search for their spells and roll to be able to learn them, which is really the only reason to have a ton of spells (many of which are similar). Yes, it will make casters more versatile, but you can also just let them prepare fewer spells.
For magic items, I'd borrow from 3x. For weapons and armor, have a list of traits like bane, icy, flaming, etc. Wands, rods, staves, and even rings are mostly just collections of spells anyway, so describe how to assign charge cost. For wondrous items, talk about how to make them cool and useful. For all three categories, talk about how to balance them. Then give a few pages of examples and leave the rest up for the GMs to come up with. The 5e DMG, IIRC, already does this a bit with artifacts, so why not go the rest of the way? It's not like the fanbase or 3pp authors won't come up with a ton of new ones.