Naomi,
// ... if this country introduces laws that for one reason or another turn out to be bad laws ... those laws are our own mistakes and we are free to amend or abolish them. //
How free are "we", really? Again, it's that use of the word "we" that implies some sense of collective agreement, when the reality is anything but. The current situation in the UK buries this a little by having a form of democracy whereby the "we" who are free to amend bad laws is restricted to either of two groups, neither of whom commands the support of the majority nor has ever done. Even when "we" vote one lot or the other out, the new group has an effective carte blanche for five years or so to pass whatever laws it chooses, and "we" have no say in that period. The freedom "we" then have to amend "our" laws is really only extended to a subset of around 1,000 people, most of which can't be held to account either in theory or in practice.
Before I get ranting too much, the basic point is that "we" are, in general, mostly far from free to set our own laws, and the freedom "we" do have is very illusory. This doesn't mean that I don't think the UK is a democracy (certainly I can't think of anywhere better). But the UK is not "we", when it comes to some collective agreement. For most of us, all of the purported problems of being in the EU will remain. Locally and nationally, "we" will have to accept laws that "we" have no say in, or disagreed with at least, and a limited opportunity (and, in practice, no opportunity at all) to change those laws.
The "freedom" the UK gains on leaving the EU is therefore highly deceptive. "We" won't even necessarily be freer when it comes to defining our international relations; "we" will still have to make compromises, accept deals, make concessions. Short of withdrawing from the rest of the world entirely, it is certain that "we" won't always get what "we" want.
It won't even be necessarily any better with the EU. We will still have to accept their rules, to some extent. How far depends on the deal we get, but again the only way to avoid the EU and its rules entirely is to turn our backs on it, and that is completely unfeasible. So we deal with them. And then comes the choice: deal with the EU from outside, or from within? In, and we can change the rules (and despite being overruled a few times, we have changed some rules, and quite significant ones at that). In, sometimes, we don't get our way, and the rules go against our choices. But we have some chance to amend them. Out, we have no such chance, ever.
If you like, this is simple a larger-scale version of your "if we don't like the laws, we are free to amend them" -- albeit with the modification "we are free to try to amend them", but then being free to try is the best freedom one can ever really have in a democracy, or in a large group of nations in general.
Apologies for this post going on so long. I've actually pared it back a few times...