Originally you said:

I no longer desired to live forever. I didn't even desire to live longer than about a century.

That's just part of my history. I carefully put it in the past tense.

Then I wrote a paragraph saying that I no longer had any particular opinion as to how long I should live, that I would just see it day by day. Actually, the paragraph covered more than that, including how I transitioned from a feeling that a century was about right to the idea that it was silly to judge such things. But then, on proofreading my original post, I cut that paragraph. So now my original post reads

[…] I didn't even desire to live longer than about a century.

And since I no longer desire to live so long, […]

The transition from past tense to present tense is not very clear there, for which I apologise.

But currently I have no particular desire about my length of life. I could make a prediction, based on what is likely to happen in the future and what I am likely to want, as to whether I will always want to live a bit longer, and if I predict that I will, then I could say now that I want to live forever. But signing up for cryonics now would not help me achieve any of the wishes that I anticipate having in the future, because that's not how I'll want to live longer. (And if this prediction is wrong, then I can sign up later.)

You almost seem to be viewing the question of whether you value a long life as fundamentally different to the question of whether you would want to continue living on any given future day. This seems bizarre to me.

In that case, taboo wanting to live forever. For some people, that seems to be a value for its own sake; I think that it was for me once. But now I'm rational like you, and I only want to live forever if I'll forever want to live. So the only question is whether I want, assuming that I get hit by a bus today, to wake up a hundred years later. And I don't particularly.

But once upon a time, I really wanted to live forever, because I liked the idea of living forever. In holding this idea, wasn't thinking about whether some day I would like to die; it was, if not a terminal value in its own right, something close to that. Furthermore, death was scary and unknown, and I was taught about Heaven and Hell; even after I realised that this was a fairy tale, I harbored an idea that death was bad in and of itself. There are probably good evolutionary reasons why somebody would feel this way.

Once I was cured of all that, however, anything that might have made cryonics inviting was gone. That was the point of my original post.