The Chicago Manual of Style (15th edition) says about lists:
1.44 Is a list needed?
In a book with either very few or very many illustrations or tables,
all tied closely to the text, it is not essential to list them in the
front matter. Multiauthor books, proceedings of symposia, and the like
commonly do not carry lists of illustrations or tables...
12.52 When to include a list
Not every illustrated work requires a list of illustrations. A journal
issue rarely uses one. The criterion is whether the illustrations are
of intrinsic interest apart from the text they illustrate. The
illustrations in this manual, for example, do not fit that criterion.
But a book on Roman architecture, illustrated by photographs of
ancient buildings, would benefit from a list. A list of illustrations
may occasionally double as a list of credits if these do not appear
with the illustrations themselves...
I agree with this: the criterion is whether the illustrations (or tables) are
of intrinsic interest apart from the text; if they meet the criterion, lists might be of invaluable help; otherwise, they can be superfluous.
Regarding theses, lists of tables and illustrations are often a required mandatory item, even if there is no real need for them, but it is well known that some universities are not precisely known for their good typographical practices when it comes to theses.