MediaWiki is to serve Wikipedia pages. The prime objective of Wikipedia is to share in the sum of all knowledge. In order to achieve this goal, the content has to be readable and get to its audience. Once this is accomplished, any further improvements are the icing on the cake. They are the nice problems to have.
The Webfonts functionality was introduced to prevent "tofu". Tofu is named after tofu, the soya based ingredient, because it is typically served in rectangular blocks. When you are served tofu, you do not get to see the meat of the matter. You cannot read what is on a page. Consequently, Webfonts were introduced to prevent this epic failure.
As mentioned before, when the same technology can be used for cosmetic reasons, it will be used for a secondary goal. When the requirements of such secondary goals prevent the primary goal of serving data, the priorities are dead wrong.
When the use of Webfonts for cosmetic reasons is considered, the bandwidth it uses is a luxury, the performance it asks of servers is a luxury. This does not make Webfonts a luxury, its primary purpose is still to prevent tofu and consequently serve our prime directive. Consequently, it is not a question for any operations staff to consider if Webfonts should run or not. At most it is for them to decide if Webfonts in its current incarnation is good enough to serve fonts to make Wikipedia look pretty.
This issue is not understood by many people who dabble with the Wikimedia infrastructure. This becomes clear when you read some of the responses to the excellent explanation by Niklas. To put it bluntly, the decision if primary functionality can be removed is not an operational but a business decision. Given the consistent failures to protect this primary functionality, it has become an issue for the highest level of the Wikimedia Foundation.