I think it has a lot to do with what your goals are and/or why you are taking it...
- Isolate is awesome PWO. I understand that you don't "need" it, but if you are lifting heavy or high volume often, you are probably trying to maintain muscle mass if not trying to add. Whey does not "bulk" you up, the rest of your diet may, but a few servings a day does not.
- would love to bring whole food to the gym but would be a but expensive to eat high quality protein after every workout, whey is very convenient.
- Great to add to plain yogurt for a very low carb snack, also saves money with smoothies etc.