This would give you a database of how players play, and IMO would be bad for the overall game.
Personally I won't mind if you could replay all your matches from before.
Yes, you can study your opponent and completely analyse his way of play but that makes it more serious as well. And let's be honest,...after a time you automatically know which opponent likes to play on which way. Like this, more opponents will seriously analyze their matches and this will bring a higher level of play I think.
I know you can watch complete games from top players as outsiders on Metaforge.
Like this, you can also study the moves of a certain player.
It also means that you have to adapt yourself all the time if you're a regular top player.
So there's constant movement and you have to prepare more for battles.
I'm in favour of this. I think all people should be able to watch battles from other people and it's also nice to see past matches from your opponent.
With those options, you'll always have to be ready to have a surprising element in your army for every time you play. You can't risk to play with the same set-up, you gotta re-invent yourself the whole time.
It gives a new dimension to the game.
If i could see all the matches from Spiff, damn,....I'd study every detail of it so I finally know how he does it every time.