It's also size thing. Small helicopters with skids are fairly easy to move, but the task becomes more difficult as the aircraft grows. Imagine trying to move a Sea King/Merlin with skids.
Wheeled undercarriage, especially when retractable, is heavy and expensive. So, with smaller aircraft the weight takes up a high percentage of the aircraft's weight and cost. As the aircraft get bigger, that percentage gets smaller so becomes more viable.
I think you'll find that the crossover point is around the Lynx/Bell 412 size.