It has been reported, and I believe confirmed, that Browning did not like manual safeties and that he felt that on a hammer gun the only safety needed was the half cock notch. (No Browning-designed hammer rifle or shotgun ever had a manual safety until recent years.) The sight safety appears to have been the Colt company's idea, not Browning's.
Both the grip and manual (thumb) safeties on what became the Model 1911 were demanded by the Army, over Browning's objections.
The major drawback to the dual-link design was not the safety or lack of it, but the fact that if the gun was fired without the slide stop ("wedge") in place, the slide came back in the shooter's face. (The Army didn't think much of that, either.)