The feed I get from the local mill is mostly medicated. Actually, the Grower that I normally get is almost always medicated - until this time. The layer feed I use in my mix is often medicated as well.
So I feed medicated because its what's available to me. Do I *need* medicated? No.
But there is no harm in it, and the alternative is spending $10+ in gasoline to buy 50# bags of Purina Flock Raiser at $0.48/lb instead of mixing feed from the local mill at a cost closer to $0.29/lb (and a much shorter drive, maybe $1.50 in gas)
/edit to add, if I had a prior coccidia outbreak on my grounds, Medicated would be much more important to me. But I have a closed flock on virgin ground - no outside birds in almost two years, and I'm hatching what I raise. That makes my risk profile somewhat smaller than that of many others.