"The Unicode Consortium is a non-profit corporation devoted to developing, maintaining, and promoting software internationalization standards and data, particularly the Unicode Standard, which specifies the representation of text in all modern software products and standards."
The fact that it is their goal to set the standard for the textual representation of human speech means that they take on that responsibility.
Wikipedia is not forced unto the world as everyone's only source of knowledge.
Unicode on the other hand is the only way many people have to input and see text in their native language. When one group proposes being the ultimate solution to everyone's problems, and then pushes their standard forward as such, complaints about inadequacies in the solution presented are perfectly fair and valid.
Unicode is not "forced" unto the world either. It's just a good way to do the thing it does, but it doesn't happen without contribution from those who are impacted.
The word is "unicode". "Uni" as in "united". Wikipedia doesn't claim to be the One True Encyclopedia, but with Unicode it's literally right there in the name.
The fact that it is their goal to set the standard for the textual representation of human speech means that they take on that responsibility.