The question is why haven't you. Leveraging one program's offer at other programs for quicker responses, better financial packages is a long accepted practice. Applicants to universities have done this for ages.
Remember you are the paying customers and have all the leverage and not at the mercy or whim of any program. If you are not comfortable asking them to give you faster communication on the decision NOW, how are you going to ask them for more important things like internship/job support LATER?
Lastly, it is encouraged that if you have offer deadlines, you should tell the programs so they can put it on an express line. Not every program will honor this practice but they should not use this against you in any way.
There are many better programs out there so you have to optimize your time. Get them to work for you, not the other way around.