They were not wrong to ask the question, but they asked the wrong question.
Given the miracle of Jesus' resurrection from the dead, being instructed by him and being promised the Holy Spirit and power in a few day's time, they might have felt as high as kites, that their time had come to rule with Christ in his kingdom. After the crushing despondency of Christ's crucifixion, they now were elated, raring to go.
Their question, then, was reasonable from their point of view. It wasn't a stupid question. It deserved - and got - a truthful answer that helped redirect their thinking. However, it wasn't a straight, "No. I'm not restoring the kingdom at this time." Why not?
Because that would not have been the truth. Jesus was seconds away from being uplifted into heaven, bodily, to go back to the Father to sit at his right hand in glory as King of the Kingdom. Remember all his parables about a man going to a far country to receive a kingdom (before returning)? The disciples must have forgotten all about those. But Jesus WAS restoring the Kingdom, by that very act of leaving them to return to the Father. They wouldn't see what he did in heaven, of course. Nor did they know the time gap between their Lord receiving the Kingdom in heaven and returning to earth to execute justice on rebels against it.
That is why Jesus wisely answered them as he did, assuring them that they would get what they needed to do as he was now commanding them, if they waited some days in Jerusalem. Then they would be able to do the global work that lay ahead. That was to be their part in furthering the Kingdom - being Christ's witnesses.
The relevance of Jesus' answer was that he (effectively) told them, "No, I am not," from their point of view. Yet he did not actually say that because he was, at that time, restoring the Kingdom, just not in a way or in a place that they expected. Because he knew the vast time gap (from their point of view) till his return to deal with the earthly aspect of the Kingdom, he focused them om the work in hand - their role in supporting the Kingdom and helping to expand it, which they had to concentrate on.
That is why the book of the Revelation was given to an aged apostle John - to encourage the new Church to maintain hope in Christ suddenly returning while knowing that they would have to suffer before then. World events and unseen spiritual events would have to play out over time, eventually culminating in Christ appearing in great glory. Every century, every generation of Christians have that prophetic word to brace them for whatever stage of fulfilment works out in their age. Meantime, they get on with the work Jesus has given - witnessing to him and proclaiming the gospel of Christ faithfully. Astoundingly relevant, both then and during the near-two-thousand-years since!