right, I have spent some time thinking about this and having watched the videos have a bot of a view.
Firstly the videos you see with stumps flying everywhere are typically against real tail end bunnies.
I think it is an excepted fact that lower order players have been forced to work much harder to become multi-dimensional players and are now much more capable batsmen than previously. This has been helped by the improving kit they can wear.
As for top order players. Certainly techniques have changed. Much like speeds of race horses I don't think bowling is faster now or then. I think there are fast bowlers now as there were in previous generations. You can't tell me Finn, Stein etc are massively quicker or slower than bowlers from the past.
As touched upon there has clearly been a slowing down and flatening of pitches. Anyone who has played on an uncovered wicket will know the bounce and pace on the pitch can vary considerably, which can make a bowler appear faster or get more bounce.
Realistically o wouldn't fancy any of holding, lillee, Thompson or lee, acktar, harmisson or Finn, stein, morkle or a pumped up tino mind the Windows.
Even with the best body armour!
Personally I do think batsmen do have better techniques now than in the past, I think they spend more time at practice, it is significantly easier to review the areas of concern, analyse bowlers and thus improve.
I also think spinners are much much better now than in the past. But that is a different thread...