I think a lot of what is being said in this thread is way off base. The practice of Aikido has nothing to do with 'reacting' to your opponent, except insofar as we try to unlearn 'reaction' in favor of response. A reaction is an instinctual, habitual, or otherwise unthinking action that happens after an opponent's action or outside event - like flinching.
Aikido, or any decent martial practice, is largely about replacing reaction with response. Yet it's not just about substituting one resulting action for another - part of what differentiates one from the other is active engagement with the situation, such that that which you respond to is not so surprising or random.
As far as the comment about having never tried deliberately presenting a target to the attacker - if so your practice or instruction is lacking. You should be doing this every time you practice a technique. You and your partner establish ma-ai, then you present the target to signal uke and present them with an attack opportunity. I see this misunderstanding all the time when people expect to receive a munetsuki with their hands in the way, or a katate dori with their arm dangling limply at their side. No. You invite the attack, you present the target.
As practice becomes more advanced, you strive to influence uke's actions earlier - my understanding of the Aikido ideal is that the Aikidoka's energy-awareness-connection becomes so keen and penetrating that the attacker begins to fail as soon as they decide to initiate a particular attack.
Perhaps the most illustrative practice for this kind of awareness extension is multiple attacker randori. If you are in a 'reaction' mode, you will be swarmed and overwhelmed. The only way to fare well is to choose who will attack you and go out to meet them in a pattern that is largely of your choosing.