Directions connecting a planet with 0 degree Aries can reveal a lot. But is it useful to direct that degree itself? E.g. using the solar arc. - (In Uranian astrology = Hamburg School of Astrolgy - that degree means "generality", in mundane astrology it means the world in general.)

Yes, it does.
Witte considered it to be the most important point of the horoscope next to the MC.
It shows You in the World.
By Solar Arc, planets connecting to the Aries Point or the reverse is a good way to see how your natal planets are manifesting in the world. Depending on the other directions and transits happening at the same time you will see something unfolding with the nature of your planet.

Best to you,
Ouranos

Thanks,
yes, this seems quite convincing. I looked at some charts (at ransom) and found that including that degree can indeed give some useful information.
Apart from that I think it's also worthwhile considering the house in which we find that degree.
Regards, LL

Check also the midpoint Aries Point/Planets. Formula is simple: Planet zodiacal degree / 2
Very revealing!
And concentrate on the hard aspects to this point (0, 180, 90, 45 and to some extent 22.5). More so, when you have a natal planet and a transit at the same time.

Keywords taken from the Rules for Planetary Pictures

AR/MC = The "I" embodied at this place in time.
AR/AS = Meetings, places, locations. When you plan a meeting, check this midpoint.
AR/SU = The body, problems and matters of daily life. Several people. Who is at the center stage.
AR/MO = People and countries. Public.
AR/NN = Union of many persons, international alliances, connections with the general public. Global network.
AR/ME = General news and opinions. Medias. The youth.
AR/VE = Love in general. Music shows or arts in public.
AR/MA = Labor, forces of nature. Injuries. Work and activity in public life.
AR/JU = Good fortune in general. Money, law. Success, luck, joy. International justice.
AR/SA = Separation, parting or death in general. Disturbances or losses for many.
AR/UR = Sudden events, eruptions, explosions. Reforms. Excitement in world public. Earth science.
AR/NE = Disappointments. General poisonings. Deception, negation, confusion in the world. Public air or water.
AR/PL = General changes, transformations or developments. Plutocracy. Metamorphoses.
AR/CU = Sociability. Joint-stock company. Getting married. Public associations and communities. Social affairs.
AR/HA = General poverty, misfortune, plagues. Coal mines. Worldwide disease. Contaminated areas, catastrophes.
AR/ZE = Forces of nature. Wars. Procreation. Fire in general. Railroads.
AR/KR = Great events or nations. Governments. The authority of the general public. Major events on Earth, like when Kronos crossed the Aries Point in Sept 2001.
AR/AP = To spread out. Quantities. Commerce. Sciences. Trade. General recognition, honors, success. Freedom and peace in general. Religions.
AR/AD = Circulation. Rest, standstill. Resistance of the general public. Reduction, decrease, compression.
AR/VU = Power, might and forces in general. Violence in the general public.
AR/PO = Ideas, spirit, education, cognition, understanding and culture in the general public. Water masses or great floods on Earth. (Currently sesqui-quadrate the Aries Point and the Education system under attack in Unites States.)

Lots of interesting informtion - thank you. I'll have a close look at that -including the Trans-Neptunians! (With my astrology program it just takes two mouse clicks to get the precice midpoint.)

E.g.Hitler's chart. MC at 1-2 Leo (birth time 18:20)
MC/AR=NE (exact)
H.'s sun conj. NE via solar arc: 1918 - both a time of collapse and of reorganizing.
The complete structure is this one: MC/AR=NE=AC/MO.JU - revealing a lot about Hitler's ways of seducing his people.
Solar arc of 0 degrees AR: in 1936 it reached the VE-MA-Conj. 1936, the year of rearmament including general conscription.