There are a couple of issues with using Citation Text portion of the a citation to include the actual text from a citation (versus, for example, a Fact Note).
1) If chosen to include in a printed paper report - it will print in End Notes - which may be far removed from the sketch of the person you want it to be included. For many users Genealogy (Register-style) Reports will be hundreds to thousands pages long, with hundreds to thousands more pages of End Notes (as opposed to Page by Page footnotes - the "industry standard"). Do you really want to force the reader to "jump" forward several hundred pages to search for the "fine print" in an End Note? To include the info in the sketch of the person requires it to included in a research note, person note, or fact note.
2) If you want the info to be convenient to the FTM user of the file - the Citation Text window is a small window which only exposes a few lines of text at a time. I don't know how much text can actually be put in the Citation Text window.
That said, I think more & more users are becoming less and less concerned with paper reports. Paper reports were my primary concern for years. However, I am now much more concerned with web presentation. Whether one uses a product like WorldConnect, or ged2html, or even ancestry member trees, the citations will show on the page of the concerned person; which is the equivalent of Page by Page footnotes in printed report.
If you go to your local library and review examples of recent genealogy books and journals, you will probably find that you will come closer to those examples by actually typing sketches in the Person Note of a person, which only includes excerpts and interpretations and comments by the researcher, and then post the actual full text of wills & obits for "your eyes only" in whatever "cubby hole" makes most sense to you - either a Fact Note or Citation text or a Citation Media.
Note that Fact Notes can be globally controlled in a Genealogy (Register-style) Report; and can also be marked "private" on an individual basis - which blocks individual Fact Notes from being printed even if the global print note is turned on. Citation text can only be controlled to print on an individual citation by citation basis.