Curious, why do you see [the Airbus speed range] as an advantage? In light of this debate, the speed would still ‘wander’.
Why is "wandering" speed a problem in the descent ? (as long as it is "wandering" in order to meet the programmed profile).
It doesn't "wander" as such, it stays slightly above or below the bug until it recaptures the profile.
If ATC or the airspace specifies a speed, then of course you follow it, but if they haven't, then there's no real need - unless you are sequenced close to the one in front, (unlikely until on initial approach).
Varying speed slightly to maintain a profile makes perfect sense, and helps avoid using thrust or drag which is inefficient. (Cannot remember how helpful the Boeing auto-thrust is in doing this).
I don't know about Boeings but if you have programmed a suitable descent constraint, e.g. 8,000' at VWXYZ at 250 kts; the FMGS will meet that for you, possibly calling for more drag if needed.