It was most likely just the march of advancing technology, and they never really considered it.
The earliest version Stargate we know about are the ones from Stargate Universe. In that one, the Stargate rotated on a pedestal, which was actually integrated as part of the systems:
The next version created is the most well-known, the type in Stargate SG-1. The mechanics inside the platform have been integrated into the ring itself, which can now work on its own, provided it's propped up somehow:
When the Ancients went to the Pegasus Galaxy, there were numerous upgrades - mentioned in the pilot, including the shield that acted like Earth's iris. However, I don't believe the loss of the rotating ring was meant to be one of those features. It was probably viewed as an antiquated limitation that was gotten rid of in this new version:
The most advanced version of a Stargate we've ever seen appeared in Stargate SG-1 5x03, Ascension. It was made by an ascended Ancient, with the most advanced knowledge they ever gained. Like the ones from the Pegasus Galaxy, it has no moving parts:
There's even a real-life parallel. These are some typical modern smartphones:
There's one missing "feature" in all of these that the typical "dumbphone" has:
The body of the phone acts as a built-in screen protector.
It's a minor lost feature that no one really cares about. Likewise in the Stargate universe, remote controls existed for even the oldest gates. Normally seen controlling the Kino floating cameras, these doubled as DHDs:
So from the Ancients' perspective it was probably considered unlikely that travelers would get stranded, and so the loss of that "feature" wasn't even thought much about - it was just a relic of more limited technology.