https://yle.fi/urheilu/3-10718235
FIA's former WRC frontman, recently retired Jarmo Mahonen reveals in a Finnish interview that total of 27 countries applied for a WRC event for 2018 season. According to Mahonen, "unfortunately it's ever more often the one with the most money, who's awarded with the hosting rights".
For the calls for longer rallies Mahonen has quite a practical answer: "organizing a WRC rally costs roughly 3000€ per km". Most are probably capable to do the math from that.
Mahonen also points out, how unequal the organizers are when it comes to financial side of things. Most European rallies must constantly come up with new ideas to secure the funding, but for example the upcoming rally in Chile will be completely funded by the government.