Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?

The standard free energy of formation (${\mathrm{\Delta }}_{\mathrm{f}}{\mathrm{G}}^{\circ }$) of Cu₂S is greater than those of CS₂ and H₂S. So, Cu₂S (pyrites) cannot be reduced by carbon or hydrogen.
$2{\mathrm{Cu}}_2\mathrm{S}+\mathrm{C}⟶4\mathrm{Cu}+{\mathrm{CS}}_2 (\mathrm{Not} \mathrm{feasible})$
  ${\mathrm{Cu}}_2\mathrm{S}+{\mathrm{H}}_2⟶2\mathrm{Cu}+{\mathrm{H}}_2\mathrm{S} (\mathrm{Not} \mathrm{feasible})$
However, the ${\mathrm{\Delta }}_{\mathrm{f}}{\mathrm{G}}^{\circ }$ of copper oxide is less than that of CO₂. Therefore, the sulphide ore is first converted to oxide by roasting and then reduced.
$2{\mathrm{Cu}}_2\mathrm{S}+3{\mathrm{O}}_2\stackrel{\mathrm{Roasting} }{\to }2{\mathrm{Cu}}_2\mathrm{O}+2{\mathrm{SO}}_2$
$2{\mathrm{Cu}}_2\mathrm{O}+\mathrm{C}\stackrel{\mathrm{Heat}}{\to }4\mathrm{Cu}+{\mathrm{CO}}_2\left[\text{ Feasible }\right]$