So you are in a 210 at YSSY taking off from 34L Even if you have been given a departure from 07/25 you still have shed loads of room. You raise the gear at 30ft because that's how you do it out bush. 50 feet you have an engine failure. You now have to get the plane on the ground under control and get the gear out?
Hell I've taken 182s with retractables out of places like Albury or Canberra and been a couple hundred feet and still with runway and clearway underneath me. I'd sure rather have the gear down so all I have to do is push the nose forward when the donk dies!
Yes the above examples are simplified and exaggerated but the principal works.