These exercises are important. Grand arpeggios are helpful to acquire a good piano technique, to know the keyboard (I suggest to play them also with closed eyes) and they are much used in classical piano compositions.
Grand arpeggios in a piano composition
In this composition, arpeggios occur in both hands. Be not afraid of them. They seem more difficult than they really are. Especial care should be bestowed upon the dotted notes. When a piece or a part of one has two different endings, they are indicated in the following manner; and the rule is to play the part the first time with ending 1mo, then repeat ; omit the ending Imo, and proceed at once to ending 2mo. The object of writing a piece with two ending is to save space.
Other articles about piano arpeggios
Here is other pages dedicated to piano arpeggios techniques: