Ah, but they do serve a purpose.
There is a 20% chance of events occurring every 46 minutes if a player is within 40 meters of at least 3 base structures.
The constant stream of enemies during an event is quite useful for gathering their drops, which in turn have uses in crafting/base building. Not to mention the fact that you're able to get a nice boost in skills for your weapons and blocking skill with your shield.
And, as I said, it's only a 20% chance. Odds are you haven't noticed how many times it hasn't proc'd because well, there's no in game timer and no event happened.