I remember when I was in Greece as a missionary and a French or Italian missionary would ask me what a certain English word meant and I'd reply with a synonym—for example, I remember explaining "cliff" with "precipice".
The Americans wondered why I was explaning a simple word with a complicated one, and I was amused at that :).
The reason is, of course, simple: the "complicated" words have a Romance origin, so they're likely to have a cognate in French or Italian.
(For a similar reason, one of them told me that he had a much easier time remembering "injection" than "shot"; he also liked to use words such as "facilitate" which aren't that common in spoken English IMO.)
This would probably be the case even more for German, which has fewer Romance-derived words than English; Romance loans, therefore, tend to be even more "educated" than in English, where a Romance word is often the common expression. For example, someone talking in German about a "Possibilität" would sound high-brow or pretentious, whereas "possibility" is a "normal" word in English. (The usual German equivalent is "Möglichkeit", which might be translated into English as comething like "canliness".)
On the other hand, compounds from Germanic morphemes sometimes sound funny to me as well—for example, the Dutch "hoeveelheid" for "quantity" amuses me, since I'd understand it as "wieviel-heit", which makes sense but just sounds… quaint somehow because of its simplicity and transparent derivation. Perhaps like a word a child would create. (German wouldn't usually use "Quantität", though, but has a separate word: "Menge".)