I would trust a pediatric dermatologist
if they say its ok to do "watchful waiting" then I would trust this. There are cases when early laser is best, and I, personally, trust them to make the judgement call.
Our DD has a large hemangioma on her right hand, covering both top and bottom... it got darker at first which is normal, but then its started to lighten up at around 6 months or so.
To me, I figured that unless it started to grow rapidly/ulcerate that we would just let be "natural". Its fading now, and the doctor anticipates that it will be gone or mostly gone by the time she starts kindergarten, but if its not then we can give her the option of having laser treatment then or when she's older even. Anyhow, that is our personal situation and our reason for why we haven't started any laser treatment.
Like previous posters said there are some risks involved, and I don't know all the details but I think a baby as little as ours would have to be restrained/sedated (not without their own risks) for the procedure and it would cause some pain (?) and as others said could cause scarring of its own accord.