There are several reasons for that:)
1) to ensure the logos stay within the lore (all are the emblems of existing tribes and civilisations within the Ryzom universe)
2) transmission of those custom images to every other player out there would put strain on the servers, especially when Ryzom was created back in 2003 that was a major factor (other mmos with guild emblems don't have this same option either, btw)
3) allowing people to use their own pictures would create options for guild emblems that are abusive, offensive, racist, etc. Vetting each before it can be adopted would have to be a manual process, which is labour intensive, slow, and would cause complaints about that. Only acting on complaints afterwards could cause bad press either way, some would complain action was too slow, others that action was too harsh or unnecessary.
But 1) and 2) are by far the most important.
1) to ensure the logos stay within the lore (all are the emblems of existing tribes and civilisations within the Ryzom universe)
2) transmission of those custom images to every other player out there would put strain on the servers, especially when Ryzom was created back in 2003 that was a major factor (other mmos with guild emblems don't have this same option either, btw)
3) allowing people to use their own pictures would create options for guild emblems that are abusive, offensive, racist, etc. Vetting each before it can be adopted would have to be a manual process, which is labour intensive, slow, and would cause complaints about that. Only acting on complaints afterwards could cause bad press either way, some would complain action was too slow, others that action was too harsh or unnecessary.
But 1) and 2) are by far the most important.