DM's are here to help facilitate player RP, Not to create the RP all together. Now over the years i have had countless disagreements with the staff, However i have never had an issue getting events for good or evil groups. Why? Because i make a request and then i follow up with it if the DM's get distracted. Then i push my events and be inclusive. If you can't get four people along with you well then its unlikely to happen.Your evil factions crave attention while new ones gets it all. It's not the players' fault. The DM culture is friends and like minded people voting for friends and like-minded people into the DM team, which are more than often poeple who played good aligned character and are uncomfortable with evil RP.
As to why DM's prefer good events it has nothing to do with them playing good PC's. It has to do with good events being more inclusive and easier. A good event can generally include good, evil and neutral where as a evil event can't include good and a majority of neutral. Now what that means is the DM needs a set group in mind of evil PC's instead of just their spare of the moment event announcement. Also those Mini events DM's make for random adventuring groups, Typically require a good or neutral party because randomly starting an evil event pisses of secretive evil PC's, And would require you to check each PC's character sheet. I can tell you right now if Shar appeared randomly near my PC in anything but an event area i would be pretty annoyed although it wouldn't be the first time.