When I firsts started playint this game I was excited about the prospect of owning a keep in Cyrodil to claim for your guild. It turns out that the idea has become too volatile and keeps are horrible places to set up guild vendors cause of the constant flux.
At this current juncture being part of a guild in ESO is pretty much akin to ummm well just being part of a club with a cool name . . . There are NO perks for being a basic member. If you're lucky you'll work your way up and be able to withdraw from the guild bank, which is lorded over by some miserly guildmasters.
What can be done about this pathetic system of guild nothingness?
Well, frankly, lots can be done
1) Guilds should be able to spend gold on things other than guild vendors like boosts for exp, gold, and other game objectives
2) Guilds should have focuses when they are created that would determine a guild skill tree to make improvements for the guild i.e. say you are starting a trade guild a guild should get binuses in categories for a) number of players in guild b) number of active players that log in each week c) maybe gold stipends that are paid out as rewards for being the top seller d) reward players for specializing in selling certain types of things or maybe PvP guilds grants you access to to a guild Pvp skill line
3) ANYTHING TO GIVE MORE BENEFITS TO BEING PART OF A GUILD
Listen, I am not saying any of my suggestions are good or well thought out, but surely something needs to be done.