Exactly! The top strap vs. open top debate has been going on for years. The fact is, at the pressures generated by these pistols when firing black powder loads, either design was adequately strong.
Once the evolution to smokeless powder took place, then yes, the top strap design ultimately won out. Witness the fact that the Army would not approve the purchase of the Colt 1872 open top revolver, and strongly suggested that Colt redesign it with a top strap like the Remington - hence the 1873 Single Action Army.
In my mind though, another factor in favor of Colt's "archaic" design using a wedge through the cylinder arbor is that, in the blackpowder era, you could easily separate the barrel and cylinder - the parts that accumulated the most fouling - from the frame and immerse them in water for a good scrubbing. The frame, which did not get nearly so dirty, could just get a careful wipe down with a wet rag, then a quick re-oiling. You only had to detail-strip the frame for cleaning once or twice a year.
Can't do this so well with a Remington.
Samuel Colt has been derided as of late for sticking with his old fashioned design for too long, when other designers had gone to a window frame design. However, witness the fact that Colt did produce a line of pistols (and even a carbine version), the 1855 side hammers designed by Colt's factory manager Elijah Root, that had a top strap and a removable cylinder base pin (which was screwed into the frame from the rear, hence the side hammer design that was required to clear the base pin). Even though these were perfectly good pistols, they were largely a failure in the marketplace because the public, when buying a Colt pistol, wanted a pistol that had the features of a Colt, which in the perception of the day meant open top and a barrel wedge.