Romans weren't renowned horsemen in either case - they mostly used cavarly auxilla and more often than not, used allied horse rather than romans as such.
And my point was, that when Rome was top dog many people wanted Roman citizenship & associated benefits (it was the only way to get power & wealth for many) but once the rot set in - not many stuck around to be part of the losing side. Hence the abandonment of all elements of "Roman-ness" (sp?
) and the loss of learning and education that went along with it.
The bigger issue I think was that, because there was no-one to replace the Roman Empire when it fell (the barbarians often fought each other as much as they did Rome) the state of pretty much constant low-level warfare did not allow the luxury of time or learning to be pursued. Indeed, even in "Roman Britain" which was fairly isolated and in theory should have survived, there was a loss of control and things disintergrated into feuding warlords again.
A bigger what if could have been - what if Roman Britain had remained united and organised after the fall of Rome. It could have withstood the viking invasions and possibly the Britons would have remained Celtic rather than Anglo-Saxon as later...
