Hi Jane, it's not "wrong", it can simply be a bit unfriendly in certain circumstances. Closeness is something very Mediterranean so Spaniards tend (at least nowadays!) to reserve "usted" for very formal situations. We Catalans are even more open in that sense, and "vostè" (equivalent to the Spanish "usted") is very seldom used. Closeness is also present in other aspects of social communication, such as personal space. Anglos or Scandinavians for example, find a bit enerving when speaking to Mediterraneans (Catalans, Italians, Greeks...) in informal conversations in close proximity (fewer inches from each other than you might be used to), or the touching (ie. arm, shoulder) which might be present in a conversation among Mediterraneans -again, might, not necessarily is, and obviously this is referring to a conversation among "friends".
As I pointed, you insert the concept of respect into the sentence by adding please (when appropriate), rather than by using usted or the usted form of the verb, and most especially by the general tone of voice, which is rather interrogative or even, if imperative, is very soft, rather than harsh (as in an order: "shut up!") -it's a difficult concept to put into words, I hope I'm coming thru :))
Another nuance is that you'll use the "tu" form of the verb but will avoid using "tu" as a subject in the conversation, because then can be too direct. You can see that in the example used above: "¿Me traerás por favor una coca cola?" (or even "Tráeme una coca cola, por favor") would sound more natural these days. This sentence doesn't include the subject "tu".
In the business world, there's a practice in Catalan (also shared by our neighbours in monolingual Spain), which consists in using the "vosaltres" form ("vosotros" in Spanish) when talking to your client, even if you're talking to a single individual. It's an in-between a very direct "tu" and an extremely formal "vostè/vostes" ("usted/ustedes" in Spanish). This is to achieve the above mentioned "closeness" without stepping into the "directness" -which could be construed as overly friendly, even disrespectful,-in the business world that is! Yet as soon as the contact with the client becomes more regular, it's very common to step into the "tu" form.
Funny enough, in French -which is a distant cousin from Catalan (and Spanish)- the total opposite is true: using the "toi" form can be extremely rude, both at a social and professional level, unless there's a deep relationship between both parties.
Lastly, it's important to differentiate between generations, of course, the formal "usted" would be more general among 60/70+ than among all the other generations.
But again, don't mark my words as "the rule"... more a reflection of the real world.
PS I hope @Anna(RS) doesn't find this conversation too much "off topic", LOL!