germaine, i one of those ppl who use microwave to steam bao too. not just bao, as mentioned, i steam my bah zhang also.
The method is, i will take the cold bao from the fridge, run it under running tap water to wet the whole bao, put in a microwaveable contianer, cover it partially and put in for 2 mins (no need to add any additional water at this pt). the water on the bao will steam it through and its soft, fast and easy too.
SQ: u need to clena it everytime after u cook, then it will not be so dirty lor.
if its cluttering and u r not using, discard lah. and u can always buy a smaller more compact one if u need.