Use of 865-868MHz band & power density in EU


I am designing my own LoRa protocol with specific frequency channels for EU ETSI compliance. I did some research and saw that the band 865-868MHz is almost not used at all and I wonder why it is so? See this report on page 34:

ETSI states a Power density for that band:
"-4,5 dBm/100 kHz The power density can be increased to +6,2 dBm/100 kHz if the band of operation is limited to 865 MHz to 868 MHz. "

But I am not sure what the above requirement means and if this is a problem for LoRa messages at 125kHz bandwidth with 14dBm Tx power?

Thanks in advance!