This is another post to support the mega events that have been mistreated lately.
I started playing the easier difficulties with mega events turned on, and as far as I can tell, they are great. They especially help when after the mid game, when everything becomes rounding up ships to build influence starbases or invade enemy planets. When you are at ease only right clicking here and there, not even bothering to do check ups on your planets anymore, something comes out and wipes every ship flying around or requires you to divert your research elsewhere or forces you to take the offensive to another race. Not only that, mostly, these events are on a galactic scale, they don't affect you only, they affect the AIs as well.
I currently have them turned off, since I'm climbing the difficulty ladder (upto challenging now), but I'll turn them on again when I have tough under control.