In, more or less, a nutshell - While such things as teenagers, children, even infants getting eatin in a world as wild and untamed as felarya certanly would occur, describing such acts with any sort of gratuitous detail is generally frowned upon. The reasons for this are many and varied. he most obvious is the legal ones, especially in drawn art, one must be very careful, portraying underaged characters in anything that can be related to a sexual nature can lead to child porn allegations. Now, vore itself is not sexual in nature at all, but the fetish derived from it is a grey area that makes many unconfortable. That said, there are many media mediums (Movies, TV shows, Comics, Books, ect) that do indeed have teenagers and even children dying, often in horrendously violent ways (And yes, this includes Vore of many types, including hard Vore), In those cases though, the authors generally adhere to strict rules, not protraying the act in a sexual manner for example, focusing more on the horrendous aspect of it. In felarya, we encourage any authors or artists not to include such acts because Felarya's roots are deep in fetish territory, and to see children killed in such a setting rings alarm bells more often than not. That said, we don't say it isn't doable, and certainly it has been done before. We do however advise care and caution if delving into this aspect. Do not make it tactless and tasteless, make sure you adhere to the law, and don't just throw it out there to say that it's there, make sure there is a reason for this to be written about, let alone shown.
My own first chapter depicted the death of an underaged character by vore, however, I was not gratuitous with the detail, and it does serve as a plot-point.
The other reasons are due more to personal oppinions, tastes and other variables. Most people find that it is in poor taste to kill a non-adult in any manner