Once the astronauts were back inside the lunar module following their moon-walks, they took off their backpacks and hooked up to the on-board life support system. They then opened the door and threw out the backpacks, lunar boots, and the helmet visor assembly along with the pair of lunar gloves (they had a pair of Intra-vehicular gloves used on-board).

Why did they throw out all of the suit items instead of bringing them back with them anyway? Simple: the goal was to collect and carry back to earth rock specimens from the lunar surface and the weight had to be offset by dumping as many un-needed parts as possible.

Here are some pictures of the actual moon rocks brought to Earth from the Apollo 11 mission

So while we took a part of the moon back to Earth with us, we had to leave part of the Earth’s materials behind.

Seems like a fair trade to me.