@rhinoteknl @gbell_in_oz @cslorabox. Many of the reasons & answers are on the forum over last couple of years. As @kersing suggests, please use search. For me it comes down to 3 potential issues… 1) fragmenting community effort via disparate freq plans ( no repeat of Australia please! ;-), 2) wait for LoRa-Alliance to define & implement plan to avoid dead ends or incompatibilities & 3) frequency band limits and risk of breaching regs wrt freq use.
If too lazy or not motivated to search then FTFY 
https://www.thethingsnetwork.org/forum/t/proposal-for-eu-433-frequency-plan/13090/11
@cslorabox is spot on wrt #4 