Update The Inhibitor's Icon
Back when the map was updated (I think? I joined mid S5) the inhibitors got progress rings around them to show the time left until they respawned.
http://3.bp.blogspot.com/-dNRfDYe60CM/VCVs5PiBIPI/AAAAAAAAZ1k/oZqq3Yy86mg/s1600/inhibv.jpg
My suggestion to increase game knowledge, the same reasoning behind the Baron and Dragon respawn timers being added,is to add a visual indicator to the minimap to represent their respawning more clearly.
The indicator is a small progress circle of the team's color inside the inhibitor icon.
Ex: https://css-tricks.com/wp-content/uploads/2012/08/pietimer.png
This is a tiny, minuscule change that has obviously been thought of, albeit not voiced, by multiple people for months. (I was thinking of it for around 3 months before posting this)
This change may seem small, yet I believe that Aang can save the world that it is an entirely positive change that allows for a better, easier to learn League of Legends.
(and while you're working on inhibs, please make them targetable by enemy pings when destroyed the same way they are ping-able to defend when destroyed in your base)