Why did the Roman army base on infantry?

[Flavivs Aetivs]

The Goths are recorded to have usually dismounted to fight. They did so in Adrianopolis, and the Alamanni dismounted to fight in Strausbourg.

The Hunnic Army itself was Mostly Cavalry, but they conquered a lot of Germanic tribes and eventually became a predominately Infantry force, comprised of Gepids and Gothic troops. Although the Huns stillg ave them the tactical edge.