I think that at foreign airports, they plan on a bus gate. I'm not so sure that they are scheduled for a gate with a jetway, arrive to see that it's occupied, and then park at a hard stand.
However, I do think that airlines in the US should have the flexibility to use a hard stand if there's an expected delay of more than 30 minutes. It would take some advance planning to how the airline will be able to switch, such as getting connecting bags to the plane when it later departs.
Part of the problem might be that stairs seem to be almost forbidden possibly due to US handicapped regulations. However, there are ramps now, such as in Long Beach and Paine Field (Washington).