‘We have the technology’, as the opening to The Bionic Man used to say.

Ahem. Six Million Dollar Man. Young whippersnapper...

...I’d want to get the hell out as soon as I was old enough to realise that a place existed with blue skies, oceans, sunsets, girls in grass skirts on tropical islands, rain, wind, snow, mountains, deserts, and a respectable quota of gravity.

But what makes you think that by that time, we'd have such conditions on Earth?

...and urine recycled several million times …

Most people don't realize that's actually the water we're drinking right now. It's not hard to imagine a perspective that would rather have meticulously filtered water instead of the hit-or-miss, nobody-knows-the-path water from normal ecosystem processes in the dirt, yuck!

I suspect that space colonies and cities filled with wildly enthusiastic and excited space farers is an irrational delusion.

Despite my having some fun above, I'm much inclined to agree with you. We project out these ideas of terraforming and century/colony ships, most likely because, as Matt B says, we're explorers - it's an ingrained trait. The idea of maintaining an ecosystem that's already exactly what we need it to be somehow gets lost, despite the fact that it would be a thousand times easier.

We make excuses such as "natural resources running out," but imagine what those resources are like on a colony ship? Zero-population gain and limits on energy use and calorie consumption? Yes, implementing such would prevent the need for colony ships in the first place.

I'd love to see what conditions on other planets are like, but I suspect the likelihood of finding the classic M/Terra style is infinitesimal, and we're better off with probes. The benefit to cost of outer exploration seems far too disproportionate to contemplate seriously. I've even argued against the idea of space tourism because, other than horsing around in microgravity and taking photos of Earth, what else is there to do?