Depending on the headphone you want to use, that dongle is insufficient. My kiwi ears astrals sound worse with it and the koss ksc75 are rather quiet. This is with the EU version of the dongle, which has half the power of the US version.
It's also another damn thing you need to carry around and that can break. There's no reason not to include a headphone jack. Stop defending greedy design decisions that actively screw you over, it makes you look quite dumb.