I totally agree with your statement, Real Madrid might win, but they have little chance of making it to the semifinals. Their task this time is very difficult, they must score at least three goals to force Arsenal to continue the match into extra time.
Yes, Arsenal cannot play defensively because Madrid attack is very dangerous. Arteta must not take risks in the second leg, Arsenal must be able to match Madrid game if they do not want to lose their chance to advance to the semifinals.
If Arsenal play aggressively like they did in the first leg, I think it could be a disaster for Arsenal because Real Madrid's counterattacks will definitely be quite deadly in this second leg. Because with an aggregate of three goals, Arsenal still has to consider Real Madrid as a very dangerous team in the Champions League because if Arsenal immediately underestimates Real Madrid in this second leg, it could cause Arsenal to regret it. I also don't see Real Madrid qualifying more easily because when the match is going on, the main thing that Real Madrid has to think about is equalizing the aggregate so that they can have another chance in extra time.