Since they are no longer in the D&C, they are not doctrinal. However, I believe many parts of it are quoted in doctrinal works as well as some of the same teachings. Those would be doctrinal.
They are also published in full in the Ensign back in the 70's as I recall, but the presentation is of historical context making it doctrine that the LoF are part of LDS history.
In other words, as I believe bc is trying to make clear (if I'm understanding him correctly), texts like the
Lectures on Faith, or doctrines such as God the Father having a father etc (or Heavenly Mother, for that matter), while not in the scriptures, may still be doctrinal, and while not official doctrine, may still be
true doctrine. This has always been my understanding of the order of the Church. Anyone...anyone...can have the mysteries of God revealed to him or her, line upon line, point upon point, as soon as they are able to "bear it". Any member of the Church can essentially have the same knowledge, wisdom, and revelation as the Prophets. Unless, however, one is called and ordained to teach and interpret doctrine
for the Church, it is then incumbent upon one to keep such greater knowledge to oneself until such a time as that knowledge is brought forth publically through the proper channels of Priesthood authority, but the reception of that knowledge remains the same. As soon as we are capable of receiving and living to the level of the knowledge we seek, we can receive it.
Then there are doctrinal theories or opinions (traditional Priesthood ban explanations, for example) that may combine true principles as understood in the Church with other elements that can be safely discarded.
This dreary old hobby horse argument is so threadbare its literally physically painful to revisit it again and again and again as it can be answered definitively for anyone
actually seeking an answer to the question.