Maybe they should at least put a thin layer of copper at the bottom?

Are you kidding me? Copper's heat conductivity is at least 30% more than aluminium.

But really, if anyone wants to be extreme, use a silver plate. Silver is the best heat and electrical conductor for any single metal at room temperature. At least 10% better than copper.

You can see where the pipes gap between the Aluminum of the base and the next pipe, but the contact between the base of each heatpipe was excellent. These little gaps got filled with TIM, and could possibly cause a slight performance loss.