Yes, words tend to have a level of formality, and there are often words with the same or very similar meanings that differ only in level of formality.
While being succinct is a good goal in writing, it is not the only possible goal. Synonyms often have different connotation or tone, and sometimes we want to set a certain tone.
For example, consider these two snippets of text:
The night was black as pitch as Sally crept fearfully across the glen. Ominous noises assailed her, and she cowered in terror.
It was dark out as Sally walked across the field. She got scared at a bunch of strange sounds.
Both say essentially the same thing, but the tone is totally different. The first sounds like it might come from a horror novel, the second from a casual conversation.
We had a post on here about formal language not long ago. I couldn't find it again with a quick search. But basically, human beings consider some events to require formal language because they are very important. Formal language sets a certain tone. Like at a wedding, preachers sometimes say, "That which God has joined together, let no man tear asunder." It would mean the same thing if he had said, "Hey, these two are married now, it's like a God thing, so please, nobody do anything to break them up." Why doesn't the preacher say it that way? Because such informal language seems inappropriate to something as important and solemn as a marriage.
On that other question someone asked, Why do I need formal language? Why can't I just say, Hey, I know this is important?
For the same reason that in a horror novel you can't just say, Hey, what happened next was really scary. Just SAYING that something is scary or solemn or romantic or funny or whatever does not set the tone. You have to use appropriate words that really DO set the tone. Saying, "This joke is really funny" doesn't make it funny. Saying, "This statement is very profound and moving" doesn't make it profound and moving. Etc.