heh... i try not to link to or even mention mapcore over there, you think i want to be blamed if this place is inundated with nubs?
i'll have a more erudite and topical reply when i'm less durnk
*ed: essentially I think the barrier to entry is too high, the learning curve is too steep, the documentation is basically vapor, the custom content pipeline is fucking ridiculous and all in all there are better games to mod for. The mod scene carried HL1. It can't and won't carry HL2. Valve have shot themselves in the foot by doing so little to make it easy for us--just look how many of our veteran, prolific HL1 mappers have even released custom maps. It's just too much of a pain in the ass.