HCG is important because the testicles get atrophied during longer cycles. With this loss in mass also comes a loss in the ability to respond properly to LH with increased testosterone production once the cycle is over. Even if Nolvadex/Clomid will help to get LH levels elevated, the testicles won't respond to it well.. HCG provides a bolus dose of LH, to help shock them back into shape faster than a slight elevation would. Post-cycle I actually think Nolvadex's main purpose is to block any excess estrogen from the HCG shots, as once the drugs are gone you don't have much estrogen or androgen to deal with until T release from the testicles catches up.
Clomid is essentially Nolvadex, just not as strong. The thought that one is an anti-estrogen and the other a T stimulating drug is incorrect.
Excellent post and I agree with it 100%.