Main thing going for it is it doesn't give diminishing returns you'd get from extra planets and pops.
However, by the point Mega Engineering came up we were pretty much done with all the important things in the tech tree. All the weapons, ships, infrastructure upgrades were done. So technically, it just helps you through repeatable techs, or to gene-mod a little faster.
Shouldn't spoil too much, but it seems to also have events tied to it!