Perhaps a silly question, but here goes. If Germans can refer to a country with a "The" in front of it, why cant English speakers? Besides the fact that it sounds weird, why doesn't "The Switzerland" work in this case?
Convention, I suppose.
We do use the definite article with some country names, e.g. "the Gambia"; always when there is a common noun such as "kingdom" or "republic" modified by an adjective, e.g. "the United Kingdom"; and always when the country name is plural, e.g. "the Philippines".
But German doesn't use the article in the same cases -- "the Gambia" is simply Gambia while der Irak is simply "Iraq".
We don't say "the Switzerland" because we don't say it. I don't think there's much logic behind it.
It's probably related to the fact that we generally don't use "the" with proper nouns such as names of people -- we similarly don't talk about "the New York" or "the Curtis", and similarly not "the Switzerland". (But we do use it with rivers, e.g. "the Nile", and I believe this may be the origin of the usage in "the Gambia", where the country was named after the river.)