This is the reason why the Bc1-g5 idea was considered premature in the past. With the pin broken, it is not very obvious what the white bishop is doing on the h4-d8 diagonal.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1c4  3... f8c5  4. d2d3  4... g8f6  5. c1g5 The modern treatment of the position. 5... h7h6  6. g5h4 