- make things readable
- make things look good
When the objective is "share in the sum of all knowledge", the first objective is what it is all about. When people can not edit, when they can not read Wikipedia articles they are interested in, the Wikimedia Foundation fails. It fails big time.
I do not mind when designers want to make Wikipedia look good. It is what they do, it is why they have their job. What I do mind is when their concerns, concerns that are secondary to the WMF mission, interfere with the primary objective.
Web fonts and input methods are part of the "Universal Language Selector"; it is software that is designed to support the primary objective. It does its job well. It allows people to use OpenDyslexic for instance, a font that makes it easier for dyslexic people to read. It allows people to use fonts for the Myanmar, Tamil, Amharic, Divehi languages and consequently edit and read in their language.
When developers complain about the ULS, they talk about its impact on performance, they talk about the availability of fonts on systems. There is no appreciation for what the prime objective of the ULS is. This lack of appreciation indicates for me that these developers have lost what it is MediaWiki needs to achieve: enable people to share in the sum of all knowledge.