I find the reasons you have mentioned convincing and I don't have anything better on my mind as of now. Just a minor thing that bugs me a bit is the slight inhomogeneity in this API as discussed before(Difference in the API of Corner detectors and other Feature Detectors, returning all the keypoint info while calling `detect` but only the locations while calling `detect_and_extract`), if the new users do not find it confusing, I am perfectly fine with it. Guess we should let the time and the new users decide this?