When you get right down to it, the V-2 was a massive investment for delivering a relatively small amount of HE. The resources would have been better spent elsewhere.
In retrospect you are exactly correct. But keep in mind at this time these were very revolutionary and experimental prototype weapons and technology. One can only imagine what could have occurred had the Nazis had more time to develop and improve the accuracy of the their V-2 rockets and the ability to mount atomic weapons on them, not to mention their jet rockets. Hitler of course was obsessed with these super weapons and diverted much resources to them. And the propaganda department also used the prospects of these wonder weapons to rally and galvanize morale during the closing months of the war.