Personally I don't mind writing biographies; it always takes longer than I expect, and is never as good as I imagine, but that's what a Wiki is for. I (or someone else) can always come back later and make improvements, but I do appreciate that writing biographies isn't something everyone on Wikitree likes to do.
However I personally feel that the person who starts the profile has a duty to make it as easy for the biographer as possible. Principally for me this relates to being quite specific about what source or sources have been used. If it's a book, who was the author, and what volume and page number is the information found etc etc.
I know with books freely available on the Internet it is possible to have a link to a specific page, which is great, but still if I am going to use correct source citations in the biography, then I need to know all those other details.
For many pre-1700 profiles (and quite a few more recent than that) not all the details about a person's life can be found in just one source. You often have to look at a variety of sources to get the complete picture. For many pre-1700 profiles, sources can conflict about some details.
In these cases I think the biographer really needs more specific information about the sources. Something like - this source confirms who his/her parents were; these sources are the basis for her/his date of birth; these sources conflict over the date he/she died etc.
Basically if there is some form of structure in place, then it should be easier for someone to come in and write the biography.