Rebalancing Spellcasting 5e

[Amechra]

I really have too different opinions about this on one hand I fell that part of the appeal of high level D&D is the bonkers high power level that spells like these represent. On the other hand I get that these spells don't necessarily fit certain play styles (neither does healing spirit, goodberry's food aspect, create food and water, or others) Pathfinder 2e has a really clean solution of giving spells certain rarities so spells like these are not in the game by default but need DM permission.

On clone in particular I personally feel that it solves a big problem with world building and high level play. I find that from a world building perspective that the easiest way to explain the world not being the Tippyverse is to pretend that the players are mostly the only people of their level. The PC being effectively immortal due to clone solves the huge (in my opinion) problem of otherwise trying to explain where the replacement character comes from. This is why I dislike high magic setting like the Forgotten Realms where it is still somehow medieval-esc despite multiple (I think) high level NPC of which Elminister is the best known example and, why I like the low but broad magic of Eberron where there is a soft cap of about level 10 with few npc exceptions (few with more then 3rd level spells even) but, magic has still effected the world in mostly logical ways. Though I do understand that not everyone shares my opinions about this which is why I like the Pathfinder 2e system of spell rarities.

The reason I referred to them as "plot powers" is that many really high level spells are either things that should be the rewards for an adventure (you have a wish granted) or a cause for an adventure (oh no, the evil magic-user has a Doom Bot clone, so we have to adventure some more to stop them once and for all!). They are things that make the plot work, and they lose a lot of their shine when you can do them every day.

Your Clone example is actually kinda perfect - why does that have to be a spell? Why couldn't that be, I dunno, a magic item or something? Why does that need to be something that one single class can grab by default?

EDIT:

I think the reason why such high level effects exist is because they are the sort of things BBEG Wizards and Litches should have and there is no reason to have different NPC and PC spellcasting systems.

That's the thing - there is a reason. PCs and NPCs aren't built on the same rules in the first place, because they fill very different roles in the game. For example, most NPCs effectively exist for a single fight, so they need a different way to pace how many spells they can throw out. In a less mechanical sense, why should your Wizard (who, if you're playing from 1st level, probably started doing this whole "magic" thing less than a decade or two ago) have access to magic that is as good, if not better, than someone who literally turned themselves into an immortal skeleton so that they could study magic forever?