As a historical researcher and writer on Native Indians, I am compelled
to respond to your statement.
It seems that part of this issue is related to terminology. The term
"Indian" or, more recently, "Native Indian", "Native Person", "First
Nation" etc. has never really been accurate in the first place; it
lumps all original cultures into one category. There have been efforts,
at least in academic writing, to remedy this by distinguishing between
cultures and exploring regional differences and histories. Thus, the
use of the term "Indian" to refer to ALL aboriginal people is fading
quickly and is usually typical of older texts or research.
Another part of this issue is cultural. The Inuit have always been
a distinctive group and have been treated as such. There is a vast
amount of writing on the Inuit, at least by Canadian researchers, and
this writing is expanding constantly. As in the south, this writing
tends to reflect the mosaic of cultures rather than lumping all of them
under one term. (It is interesting to note that US writers continue to
do this through reference to the "Eskimo", even though the term has long
since fallen out of use in Canada as imposed and pejorative).
Finally, an important part of the matter is political. Inuit tend to
live in the Canadian territories (i.e. Yukon and Northwest Territory)
under different administration and structure from their southern cousins.
Recently, treaties and agreements have been completed with the Inuit
covering huge tracts in the Peace River and Ungava regions of the north.
Such agreements are unparallelled in Canada and serve to distinguish.
All in all, while early research and writing tended to include Inuit with
the rest of the Native Indian population, their distinct culture and
geographic location tended to distinguish them in later writing. There
have been several reasons for this, but the most important is the
public realization that aboriginal cultures ARE different and must be
more closely examined on an individual or regional basis if there is to
be greater understanding. At least that's the way I see it.