[LI5] Why don't we have one universal language?

I understand that it would be difficult to teach everyone, but why isn't it being worked towards?
There have been many attempts to create a universal language, but they have all failed. [1] One of the main reasons is that people do not want to give up their own language, as it is tied to culture and history. [1] In addition, while it would be more efficient and cheaper for everyone to speak the same language, people's behavior contradicts this. [2] For example, Americans' accents have not homogenized despite the advent of TV, and people still aspire to have their own unique identities, which include speaking different languages. [2] Finally, there is no single language that is spoken by the majority of the world's population. [3] Rather, today our species collectively speaks over 7,000 distinct languages, and these languages are not spread out randomly across the planet. [3]
It's been suggested that we should all speak the same language, but there are good reasons why we won't, or possibly can't, adopt a single universal language [1, 2, 3, 4]. First, some groups would undoubtedly rebel against giving up their own language, as so much of culture and history is embedded within it over time [1]. Second, attempts to create a universal second language have failed, and it's unlikely that we would all agree on a common language [1]. Third, humans aspire to have their own distinct identities and form different groups [3]. As a result, it's likely that we'll continue to have different languages [3]. Finally, it's been argued that having one language would lead to people forgetting their roots and even part of their culture [4].