Has there ever been any discussion on adding spells like Spiritual Weapon, Mordenkainen's Sword, Black Blade of disaster?

Not sure how they would scale but even if they were so-so, I think it would be ok to have a few spectral weapons following you around attacking creatures.

You could even build an archetype (wizard probably) that would enhance them, allow you to have more than one active at a time, or even create unique versions of weapon attacking spells.

Sell cosmetics so your spell weapons have different visuals or allow weapon glammers to be applied to your spell weapons.

They already kind of have this with Flaming Sphere, should not be too hard to use that as base line code for this.