People who find words like "furthermore" pretentious generally don't have very good vocabularies or writing skills. I'm not singling gorefinger out as a poor writer (I have no idea what his skills are in that department), it's just a pattern I've noticed.

Yes, language can carry arrogance, but only when complex words are used for their own sake rather than for a good reason. For example, using "heretofore" is fairly snobby if you're talking about skateboarding, but it's not really arrogant if it's used in a legal discussion.

Writing is about using language to convey an idea on paper. Good writing is knowing which words are appropriate for conveying an idea on paper.