Are contractions of "I am" or "I would" rude? [duplicate]

Contractions definitely aren't rude to use in informal conversations. It's difficult to say why anyone would change your text on SE network that way, but it definitely isn't usual.

The only reason I can come up with is that if you're not a native speaker or your English isn't good enough, someone was trying to help save your question and dramatically edited your original text while subconsciously replacing all the contractions with no more reason than their own habit.

The editor (Nag) of your recent post on stack overflow lives in India. In my experience, Indians rarely use contractions, even in informal speech. For formal speech, the difference in use of contractions is even greater between the US and Britain and India. See Table 3.52.

IMHO, the choice of formality/informality, along with other matters of style and voice, should be left to the original poster. "Fixing" their voice to read like yours just ain't right.

I believe the quote "Don't assume malice when ignorance can suffice" works here. Whoever edited probably did not intend on insulting or being rude to you, but was probably editing your post for other reasons and default to their style of writing.

I disagree with your chosen answer, as it displays ignorance backwards. You should enlighten us on what the actual cause was, by talking to the editor.

To directly answer your question, it is not rude to use contractions, but it is less professional from my experiences. I try not to use them, but am not 100% at it.