An issue that i think we have that we usually gloss over?

Why does a certain class have 7 spells . I dont have a problem with but thats cause its not a top ap item while giving a whole other spell that also scales with ap. Even if we ignore all the other effects they give like cooldown reduction movement speed a large amount of mana. As i already said my problem is that these items that give an extra spell effect are also top ap items. Not having a problem with but another item that does the same thing is it was balanced long ago when it had 80 ability power before because it didn't also give 20% cooldown reduction and refund a portion of used mana. all of these items except Seraphs function like adding more damage for ap. Another item also does this but i dont have a problem with it because 1 it enables a diffrent play style and it isnt a one hit wonder of massive damage that item being .