Unballanced/Unhealthy rank environment

I really don't understand why riot didn't make any changes on the current ranked system. The promo system is so unhealthy that in lower brackets of play it's getting worse every season. The gap between divisions is getting smaller every day and sometimes it creates even scenario's where a division below it are stronger than the division that follows. The problem is even so hugh that these players getting matched into promo's into that division what creates a sort of false barier from moving to the division you belong.

The solution is simple and is discussed so many times over and over again. Namely removing the promo's between divisions and increasing the promo's between tiers to 10. Why didn't riot make this change this season...