So, we can make beer out of hops.
Great.
Since the dawn of time, humankind has found the way to sistill alchool from just about anything.
From rice, sakè.
From patatoes, bad tasting vodka.
From berries (any kind actually), wine.
I am quite sure someone invented a kind of alchool from corn.
So, why the limitation?
Also, you don't really eat hops, because they taste like a second place.
Bourbon is made from corn. It'd be nice to see the alcoholic beverages expanded some day, but I think that is largely dependent on coming up with specifics (recipes, and drink stats) that are ready to fit into the game. It currently doesn't make sense making beer out of just hops. Perhaps the hay could be made specifically into barely hay and it could be used along with hops for making beer. The harder liquors that don't require hops (vodka from potatoes, bourbon from corn) could be balanced by giving less enjoyment and making the colonists more drunk. Sake could be balanced by simply requiring more rice I suppose and being cheaper.