I concur wholeheartedly with your observation.

I think that the better (relevantly) pages are linked within a site is more crucial than irrelevant inbound links or exchanges!

Outside links are still great, but I think Google is placing a value on internal links as well.

There is a plethora of possible rationales, but I believe that the internal linking helps shows relevancy, accessibility, and even authenticity to Google. Sitemaps are great for this, but having textual relevant keyword links between articles and documents has really paid off for me!

__________________
W. R. Mineo