Michael Swan, in his grammar book, says that in this context the Present Perfect tense is not to be used.
1) Why are you crying? – Tony hit me.
2) This picture looks great. Did you paint it yourself?
I don't understand why the following are wrong, in his opinion. Could you shed some light on the factor I am missing?
These are apparently wrong. Why?
3) Why are you crying? – Tony has hit me.
4) This picture looks great. Have you painted it yourself?
If expressed in the perfect both of these would be what grammarians call the resultative perfect: the past event causes a state which continues into the present:
But perfect constructions are not used to present past events, as in a narrative; they are used to bring past events into the 'background' of the current discourse. Their relevance to the current discourse may subsequently be explained by the speaker, or left to the hearer to infer.
In the examples you offer, the relevance has already been presented; it need not be either explained or inferred. Consequently, there is no need for a perfect, and FumbleFingers' Perfect Truism comes into play: the principle that you don't use a perfect if you don't need it.
FFPT is a specific instance of what I have elsewhere called the Tolerance Maxim which governs speech: “Anything which should be understood may be omitted.” I was recently delighted to discover that this principle is recognized in formal linguistics as the I[nformativeness]-principle
a. A speaker chooses the less informative utterance [...] when the more informative one [...] is available (maxim of minimization).
b. The addressee enriches the less informative utterance and finds the most specific interpretation he thinks the speaker intended.†
† Atsuko Nishiyama and Jean-Pierre Koenig, “What is a perfect state?”, Language, Sept. 2010, p. 622, citing Jay David Atlas and Stephen C. Levinson, “It-clefts, informativeness, and logical form: Radical pragmatics (revised standard version)”, in Peter Cole, Radical pragmatics, 1981, and Stephen C. Levinson, Presumptive meanings: The theory of generalized conversational implicature, 1979.
