AI is there so everyone could eventually find an opponent. AI has got a timer before you can play against it because it's preferred that players play against other players.
I think the OP is asking why there is a timer during the match itself when you're playing AI. (It *is* slightly more difficult b/c you don't have an opponent's turn during which to think.)
Because if you would be able to hassle cardotron for like 90+ minutes he might become self-aware and realize that you wasted his time. So he would insert itself into the global nets and punish humanity with total extinction. And on a personal note, you really deserve to lose if you need 20 minutes to play against a GM because i don´t want to imagine the time other players lost while playing against you. Really slow player are beyond rude.
When the AI is taught concepts such as slow or rude then you might have a point. Until then I should be able to let it sit on my monitor anattended for as much time as I'd like much how I do when playing the campaign. I don't see how having other stuff to do equates to "needing to lose" when playing against the computer which literally has all the time in the world.
The AI is there to emulate an opponent in MP, to teach you the ropes so to speak - removing the timer might make new players unaware there even is a timer when they decided to play ranked matches vs real people. However, if you want to practice against the ai without timers - you could always use a custom map without any timer limits.
New players are already unaware that there's a timer because there's nothing in the game that prompts you towards its existence. That's mostly what brought about this post. I played this exactly like I'd been playing the campaign up until the point where I was prompted to go try a multiplayer match. The timer isn't big and "annoying" enough that it can be expected to be noticed if one isn't told to look for it--sure some might see it, but not all (I obviously didn't). So I'm not trying to be argumentative, but if this were the case, the player would first have to be notified that there is a timer to expect different behavior. I played the game exactly as I had been without being prompted to play different (e.g. being told that there is a timer and that I can't leave the AI unattended).
If I recall correctly (which happens I don't from time to time), there previously were a timer in sp adventures - which was removed quite a while back in beta, due to the arguments mentioned above. Maybe allowing a "pause" function for ai battles could work? Not sure how much code that would require however.
