It ani't that simple and it is definitely no fact, it is your opinion. Now I cannot speak for 1E or 2e, I never owned the rulebooks, I just rolled the dice my DM told me to role. I just had a quick look at the Basic Red Box rule books, the whole players handbook is 64 pages. There is 8 pages of games concepts explained via an adventure narrative, followed by 5 or so pages on the character. There is a page on town business and a solo adventure that goes from page 14 to page 22. Page 23 to 47 is character classes and a couple pages of charts, sample character sheets, sample characters and a sheet of graph paper. Page 48 to 52 is how to create a character and the remaining pages are about mappers, callers, order of march, alignement, dividing treasdure, combat encounters, hirelings and a glossery and 2 pages of ads.
The DM book has 2 pages of introduction, 9 of sample adventure and the reat monsters, treasure and charts.
Aside from the couple of paragraphs on ability checks and the retainer ruls there is nothing in the Basic books I would call non combat rules.
BECM is FAR more than just that red box DM's book! Oh my!
There is an abundance of non-combat material in the Expert, Companion, and Master sets. And then there are all those Gazetters (14 of them) filled with noncombat material. Plus the Almanacs.
1st Edition had two whole hardbacks dedicated to non-combat... the Dungeoneers Survival Guide and the Wilderness Survival Guide. Plus, a fair bit of the DMG.
2nd Edition seemed to have a book for everything, including all the noncombat aspects of the game. Several just on campaigns. Even a book for building and running a castle.
And I didn't just start posting after the first 4E books appeared. We've already run through most of what 4E will likely cover, and so far that we are already seeing "4.5" rulebooks (called Essentials) being done. And after all that, I just don't see much emphasis at all on the roleplaying (noncombat) side of the game.