You asked why any bits of psychology in the Gospels (even Thomas) are almost always turned into injunctions. Well, a mass religion is not going to be an aid to developing higher level psychology.
But some psychological insight may go into selecting the descriptions of purely higher level psychological reactions in the Gospel of Luke:
… and him that taketh away thy cloak forbid not to take thy coat also. (Luke 6: 29.)which not only advocate behaving in a way depending on higher level motivation, but invert the crucial psychodynamic of normal or anti-higher level psychology. Not only does normal psychology have no psychodynamics in favour of acting in this kind of way, but its very strong and crucial psychodynamics is to act inversely. Meanness and refusal is the distinguishing characteristic arising from belief in society. Believers in society swarm past the Little Match Girl, refusing to buy her matches which she wants to sell them to save herself from freezing to death.
Give to every man that asketh of thee; and of him that taketh
away thy goods ask them not again. (Luke 6: 30.)
One may observe in passing that the idea in modern oppressive society is to turn the believers in society, who shun the matches of the Little Match Girl, into agents of the collective - social workers, doctors and teachers who will have power to interfere in her life, and so be able to oppose her and refuse to give her what she wants more actively and continually. This will save her from freezing to death until she dies in a decentralised state in an NHS hospital.
The obvious effect of injunctions to generosity is to associate them with a social ‘ought’. Anyone with a glimmer of pre-higher level psychology who finds attractive at least the idea of giving people what they want is likely to realise that he does not actually have the motivation to do this, at least not very much, and will feel guilty and inadequate. In any case, the injunctions associated with an authoritarian ‘ought’ will arouse resentment, by reference to childhood experience, especially in those who were not brought up as only children.
All other vague psychological directives in the New Testament are only applicable (I mean applicable in a sense that is any use for developing higher level psychology) after the belief in society has been eliminated. It is only then that injunctions to single-mindedness have any real point, and anyway would probably be unnecessary.