Why is Purim an eis ratzon for tefilah?
Some explain that it's based on the din that requires us to give charity to whoever asks for it on Purim, no questions asked. When we approach G-d with our hand outstretched, he has to give also, no questions asked.
Rav Shteinman offered a different reason. Drive around any neighborhood on Purim and you see people giving gifts of mishloach manos to friends and neighbors. You see money being given to poor people. You see yeshiva bochrim collecting for one institution after another. When Jews express such love for each other, says R' Shteinman, when Jews are willing to help one another, it's no wonder that G-d is happy and is willing to listen to us.