INNER TURRET SHIELD FIX IDEA!

I made a thread about this yesterday and a very good idea posted by /u/sarengo was for inner turrets to only grant shields to allied champions after the outer turret in its respective lane has been destroyed.

Riot have stated that the shield was implemented to prevent sieges from being too overwhelming and to make inner towers more defensible. With the shield always being active however, it allows anyone to protect themselves from damage that telegraphs itself first (Karthus ult, ignite, Malz E etc.) simply by rushing under their inner turret.

Riot never said that this was the intended purpose of the shield, so why not simply change it to activate as soon as it becomes targetable by the enemy team?