
Yeah, the thing about fresh is not really why the rulesets are changed but a side effect. Then again some scenarios might work better with a different kind of ruleset. On LT39 swordsmen and riflemen can attack from ships but on LT40 only marines can do this.
The main purpose of the changes is of course making the game better, more realistic and even more fun to play. Fresh is indeed a side effect of this even while it's nice that even the veteran players can't be really sure about the winning strategy when there are changes.