Oh, they are chained all right, just not 'chained' as we might know it.
The verses you quote in 2 Peter and Jude harmonise perfectly with another statement about demonic forces in the book of the Revelation:
"And I saw an angel come down from heaven, having the key of the
bottomless pit and a great chain in his hand. And he laid hold on the
dragon, that old serpent, which is the Devil, and Satan, and bound him
a thousand years. And cast him into the bottomless pit, and shut him
up, and set a seal upon him, that he should deceive the nations no
more, till the thousand years should be fulfilled: and after that he
must be loosed a little season." (Rev. 20:1-3)
But the Luke 11 verse you quote simply shows how curtailed the activity of those evil spirits are, as they await the final judgment. Their freedom to traverse the invisible heavens, unrestricted, has long gone. They are chained by the power and authority of Christ's name. They cower before His person, doing what he commands them, even while he walks on earth. They have to ask his permission to enter into a herd of swine, to temporarily spare them going to what they dread the most - that Abyss (Luke 8:26-33). Christ's disciples see the demons flee when they use the name of Jesus. And when the 70 reported this to him, Jesus rejoiced, "I saw Satan fall like lightning from heaven" (Luke 10:17-18).
This shows that your sequence of quotes is out of order. You should have put the Luke one first, then asked how the 2 Peter and Jude verses are to be understood in light of demonic activity in the time of Christ. That's where the Revelation verses would then make sense.
This, however, is a question about how to interpret verses. It's not strictly asking a biblical hermeneutics question because the verses you mention do not, in and of themselves, provide the answer you seek. Everything will depend on your interpretation of future events, and correctly understanding the 'time-line' for what happens invisibly, to invisible demons. None of the texts you cite provide such understanding.
But a very simple point is that there are long chains, and there are short chains. The shorter the chain, the more restricted the prisoner is. What we do know from Revelation is that there is a future judgment, which the demons seem to know more about than many readers of the Bible do, where everything stated about their punishment will culminate. Right now they are cast out of God's holy heaven, restricted to invisible activity on earth; the biblical imagery is similar to them already being chained, and that chain slowly and gradually being pulled in, getting shorter and shorter. Yet that imagery is symbolic, not literal.
Once symbolic texts are seen in their symbolic sense, then the idea of literal chains disappears, but many people try to mix up symbolic verses with literal interpretations. That is why this question is not really a hermeneutic one, but a matter of interpretation. The two verses in question (which mention chains) cannot be lumped together with that verse about invisible demonic activity triggered by the presence of the Son of God walking on earth.