What is an eruv - cop-out or practical expedient?

I recently encountered the concept of an eruv (pl. eruvin), and I can kind of see what it is not something that Jewish people talk about much, and why I've never heard of it before.
An eruv is any kind of enclosure that Orthodox Jews use to allow them to get round a religious prohibition called hotzaah mereshut lereshut, which essentially says that they are not allowed to carry anything on the Shabbat or rest day (basically Friday evening until Saturday evening). More specifically, it disallows them from carrying things from the "private doman" (such as a house) to the "public domain" (such as a road), or for more than four cubits (about 2 metres) within the public domain.
Apparently, this whole prohibition arose from a specific verse in the Bible (Jeremiah, 17:22-22), which Jewish medieval scholars decided to take literally and interpret in a very specific way. You can almost imagine them sniggering in their monastic cells, as they come up with yet more prescriptions to make the lives of religious Jewish people more difficult (all for the greater gloriy of God, I'm sure).
Anyway, an eruv is way of combining and extending private and public domains - eruv chatzerot literally means a merging of different domains - so that the rather random injunction against carrying anything on the Sabbath day is not so onerous. It may take the form of a courtyard or an apartment complex or a walled city or a fence, or, in modern cities, it is often a high wire supported by wooden poles similar to telephone poles.
Almost every Jewish community in Israel has one, as do most large North American cities (including Toronto) in the main Jewish areas, and you can even check online to see the status of the eruv. Many other cities around the world with large Jewish populations also have them, including London, Vienna, Amsterdam, Rio de Janeiro, Sydney, Melbourne and others. Apparently, there are raging debates in Jewish scholarly circles in some of these cities as to whether particular eruvin are valid according to the various scholarly commentaries on the subject, which has to be on a par with angels dancing on the head of a pin as far as religious debates go.
So, there you go: eruv - lazy cop-out, or practical interpretation of a ridiculous religious law. You choose.