For all of its struggles during its relatively short existence, Twitter (NYSE:TWTR) had a clear identity.

In the social media world, Facebook (NASDAQ:FB) is the juggernaut where everyone from grandma to that person you barely remember from high school posts status updates. LinkedIn (NYSE:LNKD) is the Facebook for business, and Twitter is the social media site with the 140-character posts.

Twitter might struggle to monetize its audience, and it will almost certainly suffer from simply not being as bog as Facebook, or as laser-focused as LinkedIn, but people clearly understand its premise by boiling it down to the brevity of posts on the site/app. Even Facebook posts are not as distinctive, nor do they have a dedicated name. There are now "Facies" or ""Links," or whatever else you might name posts on those sites, but Twitter has its Tweets, and everyone knows what that means.

Despite all of its struggles -- and there were many this year, including the resignation of CEO Dick Costolo -- Twitter could still hang its hat on the idea that it had a clear identity built around its 140-character limits on all interactions on the site. Be they Tweets or direct messages, the limit applied, which, while sometimes frustrating, was at least distinctive.

That, of course, made it very peculiar when in August, under the auspices of then-interim, now-permanent CEO Jack Dorsey, the company dropped its 140-character limit on direct messages.

What did Twitter do?
The social media platform did not remove the 140-character limit on Tweets. It only got rid of it for direct messages. On some levels, that's convenient, but there are some major drawbacks.

Anyone you follow and are followed by can direct message you. That meant that if you casually followed someone you actually have no interest in speaking with, that person now has the ability to send you a long message. The company explained the change in a blog post that also inadvertently laid out why some people may not like it.

Direct Messages let you have private conversations about the memes, news, movements, and events that unfold on Twitter. Each of the hundreds of millions of Tweets sent across Twitter every day is an opportunity for you to spark a conversation about what's happening in your world. 

Of course, if you wanted to have a conversation with someone, there is a pretty good chance they would have your email address (or even your phone number). At the very least, he or she would be your Facebook friend and could message you on that platform.

Why is this bad?
Twitter built its platform on brevity. Forcing even direct messages to be under 140 character kept all interactions to a certain level of directness. Yes, you could send multiple messages, but most people recognize that doing that makes them look a bit crazy.

Short interactions was Twitter's thing -- its reason for existing. Without it, the platform becomes a third-, perhaps fourth-tier way for people to communicate. Twitter without a character limit is KISS without makeup. It seems like a good idea at first, and then you quickly realize what a blunder it is.

Anyone you would have a conversation with requiring more than 140 characters per comment can reach you in other ways. Dropping the limit, even if it's only for direct messages, sacrifices brand identity for something few people actually want or need.

Daniel Kline owns shares of Facebook. Follow him on Twitter @worstideas. The Motley Fool owns shares of and recommends Facebook, LinkedIn, and Twitter. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.