A heavy airplane taxiing at a slow speed will increase a significant increase in wheel and brake temperatures simply from sidewall flex. A very long taxi (typica at places like Amsterdam) can result in elevated brake temperatures upon arrival at the runway. This in tern has an effect on the available brake energy in the event of a rejected takeoff, and if the temperature is high enough may also require leaving the gear down for a short time after takeoff...especially if the leg length is short.
After landing, the same thing applies. Sitting with brakes applied can increase brake temperatures and heat wheel assemblies, warp or damage brakes, and even seize brakes.