Or 1...f5 2.exf5 Bxf5 3.Bg4 Bxg4 4.hxg4 , intending 5.Bxc5 Rxc5 6.Ne4 with a typical "good knight vs. bad bishop" scenario.
The bishop exchange has emphasized Black's light square weaknesses, and his next move makes things even worse.
Avoiding 8...Nxe4?! 9.Nxe4, when White gets closer to achieving c4-c5. In the game Black keeps the important c5-square under control, whereas the bishop isn't really doing anything on e4.
Preparing Bf5 in order to swap White's good bishop. Besides this, there now appears the threat of ...Bxh3.