Because the makers of the pack decided that it would fit in this version, and I kind of agree as AE2 is everywhere and horizons is supposed to show new/not so well known mods.
My understanding is that the theme for Horizons is to showcase some less-used mods. AE2 is pretty widely used in 1.7.10 modpacks, so I assume it was deliberately left out to force people to explore some of the other inventory management systems.
My understanding is that the theme for Horizons is to showcase some less-used mods. AE2 is pretty widely used in 1.7.10 modpacks, so I assume it was deliberately left out to force people to explore some of the other inventory management systems.
I think the answer "because reasons" is appropriate here.
AE2 is good but it sort of takes the scale away from a inventory management builds. As that's it's purpose to condense the walls of indexed organised chests in to a smaller footprint. Also automation.