It strikes me as I am learning Kesubos that the Gemara takes the time to speak of extensively the shortcomings and praises of dates (the fruit). I know the gemara does the same with cabbage and other fruit and vegetables like watercress and the like. What does the gemara wish to accomplish by giving this information if anything, what is the significance, and is there a significance to its placement to this information? Or is the gemara just plain old giving food and health advice?
There might be a few possible reasons:
It might indeed be "plain old giving food and health advice" - maintaining proper health is important in being able to serve Hashem without disruption, after all. Indeed, Rambam begins his recommendations for a healthy lifestyle (Hil. De'os ch. 4) with exactly this point: "Since maintaining a healthy and sound body is among the ways of G-d - for one cannot understand or have any knowledge of the Creator, if he is ill - therefore, he must avoid that which harms the body and accustom himself to that which is healthful and helps the body become stronger."
In particular, these statements and recommendations are of help to Torah scholars, helping them to make the best of their (usually limited) finances. We thus find in Shabbos 140b a whole series of "smart consumer" suggestions by Rav Chisda, all addressed specifically to the yeshivah student (bar bei rav).
Sometimes these also shed light on other facts and statements. For example, in Pesachim 87b-88a Ulla says that one reason why Hashem arranged for the Jews to be exiled specifically to Babylonia was "so that they could eat dates [which grow there abundantly] and be involved in Torah study." The list in Kesubos of the good qualities of dates, then, supplements this, and helps us understand better how they are indeed an ideal cheap and nourishing food.
This is all on a simple peshat level. No doubt there are also deeper Kabbalistic and other reasons for this information being included in the Gemara, although I don't know of any.