First off, do you mean the EU or the EMS? These are different things, and all serious-ish talk regarding Greece's issues that has so far went on has been about whether or not it should stay in the EMS. No one has ever considered urging Greece to leave the EU altogether, as far as I know.
And that would be silly, as the EU is not all about vying for slices of a shared cake (I am not trying to downplay this though, that's important too) - but there's also geopolitics, access to markets, even protection of european values. Losing any member would be a blow to the whole Union, especially one that has been a member for a considerable amount of time. Bad for businesses operating in Greece, bad for workers working there etc. Greece should definately NOT leave the EU.
Its membership in the EMS, however, is not as important. I'm not an economist so I'm not sure what are the possible consequences of Greece abandoning the Euro, but even if they are negative (up to a reasonable extent), I wouldn't mind seeing an abuser getting some sort of slap on the wrist. That said, I would not be in favour of any punishments that hurt the punishers out of proportion. If that is the case - retribution still ought to be achieved, but by some other means. To me, it wouldn't even matter if it's explicit or implicit. And something drives me to believe I'm not the only one thinking this
Re: Greece having no choice
You may be right in your conclusions - it has little choice due to being intertwined within the Union, but are definately not right in the comparison you provided. Greece has never been coerced into joining the EU. Can you imagine German, Polish or French tanks in Athens, as there were Soviet tanks in Vilnius? :haha
You should think for just a minute before you post. Do you really want to disregard all the crimes commited by the Soviets like this?