What if i told you ap items arent undertuned?

Then there undertuned. Balance isnt a fixed point its fluctuating. If every champ is equally overpowered then there all balanced.

That's a matter of perspective then.

However since most people who have been playing over the last few seasons will have noticed that AP values have reduced dramatically will have the viewpoint that AP is undervalued by comparison

if by all the others you mean marksmen the only class people complaing about mages not being strong enough ever reference then you are correct. never i want to be strong like tanks or i want to be strong like a fighter. just adcs do so much damage can we do just as much

there is no way someone looks at rylai and luden and be "oh those items are really fine"