Currently the only way to get guild exp are tedious quest you have to do solo. How about a system like friend exp, but with guildies. So when you did anything that rewarded you with regular exp with your guild members, you also gain a very small amount of guild exp.
This would be hard to balance with the current guild exp required to level, so to balance it additional changes would probably have to be made. But I also think that a change like this is out of reach for now, but maybe it's something that could be done in combination with other improvements to the guild system later down the line.
Edited by Precrush, 26 January 2016 - 12:45 AM.