I'm not terribly fond of roasted parsnips prepared as you described. I like them better cut up in soup with other things, or boiled/steamed then topped with a little butter (I think you're right that the olive oil can be a bit odd), or I fancy up with brown sugar for a glaze for special occasion dinners (usually mixed with carrots prepared the same way). They also make a good mashed vegetable, but then there's your milk and butter and potentially cheese improving things again.