Schumann had been contemplating ideas for this brilliant work for a long time. When he had found the right form, it was published as Toccata opus 7, a major technical challenge for pianists. Schumann's idiosyncratic attempt to strengthen his fourth finger by hanging a weight on it with a string at night is well known. That of course had the opposite effect, but given the challenge that this Toccata poses, especially to the spreading of the left hand, the frustration about the difficulties for the little fingers is understandable.
The use of a pedal would of course have been very helpful in those places. Schumann later wrote regularly for the pedal piano, which he saw as a new stage in the development of the piano. Whether he himself played his Toccata on the pedal piano is not clear, but in this organ arrangement the problem for the left hand is largely solved. Furthermore, the texture could easily be translated to a performance on two keyboards. Major dynamic developments are not necessary. The different ideas can be supported with registration differences, but the work can also be performed well on smaller two-manual organs.
Some fragments from theToccata: