Give cinderhulk 5%ms and some aditional mana-sustain and no tank would really bother with runic echo.
The thing is that echo is simply a better item to rush, as it gives all a jungler would want early on, and since junglers have their biggest impact on the game early on, they naturaly go with what boost that early the most.
It gives a better clearspeed with the ap and the proc, it increases map-mobillity via ms, it makes ganks more dangerous due to more ms and burst, and it solves the god damn mana issues that many junglers have, and more mana means more everything, faster clears, more ganking opportunites, allows to use mobillity tools for efficient pathing in the jungle, increases sustain if you have a shield/heal...beeing able to actually make full use of your kit at all times is a huge advantage.
i already used runglaive on main junglers like nauti due to the way faster clears and mostly the mana, and that didn't have the sweet ms on it...
However, saying runic provides better combat stats is simply wrong, it gives about the same goldvalue of hp as runic gives ap, just that hp is a prime stat for tanks and ap is secundary at best. For lategame scaleing and especially mid game teamfights, cinderhulk is superior to runic on any tank.
I think jungle items need to provide better manasustain across the board, there is a reason that most top tier competetive junglers are manaless, or in case of elise and nida have most of their needed tools for clearing without mana...
Aditionally, cinderhulks burn needs to be buffed a bit so the clearspeed discrepancy isn't as big compared to other jungle items.