Some people can consider it as not important but I find it a bug because of the costs especially in roaming mode. The problem of the Ubuntu phone (unlike any other device starting from the ancient very first Nokia or Motorola phones) is that we don't see the length of the message that we write. Some people can say: "hey there are only a few cents difference nowadays! What's the difference between sending one sms message or two of them?". The answer to that question is very simple: try to take Your phone abroad. For example fly from Your home country as Poland, Germany, France etc. to RPA, Macedonia or such kind of countries where one single space between two words can save You a few dollars/euro for every single message. Let's say You have now badly send many of them? It makes a difference! If a message is to be send as a sms it does make a difference!
Perhaps one more small explanation: a sms message contains ~~160-162 signs depending on the signs that we use. If we are abroad and need to send a message as a sms one or two more words can make the message longer than 160, for example 168. For a 168 letter long message we're gonna pay for two messages. If we cut some spaces or unnecessary words, we can get the same message send as 158 letters and pay only for one sms.