The problem with raising the price is that it won't really cut down on noob clans being created. Many are created by nooks that use nobs cause 25bil is a hefty amount for them. Now you would need to increase the nob cost to create a clan which would likely cut the devs income so that's not going to happen
Leaving nobs as is is fine. If they are not afraid to spend money on the game they are more than likely filled with enough knowledge to be possibly make a good clan. Let alone spending the money on a clan instead if upgrading really shows something. But fot someone to come out of nowhere with 25bill doesn't say much. And I can personally say most people enjoy clans with more people to allow more interaction.
They spend money to buy a clan cause 25bil is too tough to earn. If 25bil is too tough to earn then you likely don't have much knowledge to run a clan