Although they don't seem to be in any rush - only 19 of 28 EU countries have joined the Euro according to https://en.wikipedia.org/wiki/Eurozone .

The Eurozone isn't necessarily that bad.

The main thing is that you can't tax by printing currency anymore which is a really easy way to levy taxes. That means you have to have an efficient taxation apparatus, tax the rich and poor equitably and be very careful with borrowing.

Greek's problem is that it isn't particularly strong in any of those and thus isn't really suited for being part of the Eurozone yet.

As it stands, keeping the 'poorer' countries in the Eurozone seems like a very bad idea. The main reason being that -unlike the USA- people in e.g. The Netherlands don't feel a connection with people from Spain and vice versa. People in the northern European countries don't even feel a connection with people in the countries close to them, even though the cultures are much closer aligned (in terms of sobriety, work-ethos, etc…)

This I think is the main difference with the USA. The USA also has richer and poorer stats, but because of the shared language, history and culture, people in both the richer and the poorer states feel like a US citizen.

I don't think anyone is interested in forcing countries to leave the EU if it's decided that they will leave the Euro.

No, Sweden does not have such an exception, they are required to join when they fulfil the requirements.

They just exercise some creativity by making sure they don't meet the requirements.

Sorry, I deleted that part of my post (It read "UK, Denmark and Sweden").

No need to apologize. Especially since it's close enough to an exception to remember it as such. :-)