Why do we need at all a study of quotations?

I would like to discuss some general questions to be addressed and their import on the study of quotations.

Textual-critical reasons:

• In order to better edit texts (one needs to know whether a quotation embedded in a later text is a reliable witness –this also depends on the general attitude towards the kind of text quoted). In this connection, writes K.Preisendanz: "Dense incidental as well as continuous expository commentaries […] can sometimes be used–by means of their pratīka-s and other quotations or quasi-quotations–to correct the available text of the basic work as transmitted in a dominant line of manuscript transmission which may not necessarily reflect the original text precisely; they can also make us aware of alternative versions of the basic text which were current in India" (2008: 611).
• In order to restore lost or partially lost texts. In the passage immediately following the one quoted above, writes K.Preisendanz: "[Commentaries] may even allow us to reconstruct the mūla-text of lost works. As an example […] Mallavādin's Dvādaśāranayacakra immediately comes to mind, made available through Siṃhasūri's commentary and Dharmakīrti's Hetubindu reconstructed from Arcaṭa's Hetubinduṭīkā with the additional utilization of its Tibetan translation" (2008:611-2).

Historical-critical reasons:

• In order to better understand Indian texts and/within their history (for instance, does the lack of quotations of a certain author in later texts mean that he was not influential? On the same subject, but from the standpoint of Western Ancient and Medieval authors, Ch.Schulze denies the direct link between number of quotations and fortune of a text: "Fehlende Zitate bei späteren Schriftstellern können mannigfaltige Ursachen haben –früher Textverlust, Überstrahlung durch spätere Autoritäten, Unpassendes für den eigenen Gedankengang (z.B. weil man einer anderen Schultradition anhängt als der Vorgänger) usw.–und müssen keineswegs einer Abwertung des Autors und seiner Professionalität entspringen" (2008:21).
• In order to better evaluate the relation of Indian authors to other authors (do they feel like quoting revered teachers, or do they rather name only adversaries?…).
• In order to better understand Indian habits of reading and writing/composing texts (did they quote literally even longer passages? did they quote ad sensum? did they have a small library of texts behind their desk?).