There is no reason not to pick up heath potions. At worst, a stack of 100 takes up one inventory slot. At best, they are essentially a free healing spell with a 30 second cooldown. Any little bit of healing can save your life.
Now, you definitely want to make sure you are always using the best health potion you can get. If you are out of type, another type is not used instead. You need to manually switch to them.
As a monk who likes to get right in the heart of the action, I find myself victim to a lot of spike damage. Enemies will hit me hard, but are unable to maintain their attacks before their demise. I can't spam m healing abilities, and sometimes I don't have the mana to do so anyway. Health potions provide just the boost I need to keep on punching.