2021: NoScript has between 100,000 and 1,000,000 installs on Chrome[1], and approximately 330,000 installs on Firefox[2]. NoScript is a "recommended extension" by Mozilla, and is one of the very few addons available for Mobile Firefox. (newer stats, and other reliable sources, would be appreciated. Statcounter doesn't yet reveal no-JS usage)
Internal
2015: ~3% using browsers that do not support JavaScript per Analytics/Reports/Clients without JavaScript#Preliminary results
2016: ~7% of visitors to Wikipedia Portal do not request JavaScript resources per File:Browsers, Geography, and JavaScript Support on Wikipedia Portal.pdf and File:Analysis of Wikipedia Portal Traffic and JavaScript Support.pdf
2020: Per T253033 (methodology in T234865), 13.84% of sub-A tier Desktop, and 36.48% sub-A tier mobile web page views are from browsers without JS support.
2021: Measuring the % of edits coming from users without JS enabled across all Wikimedia wikis: ~6% of logged-in users and ~1% of logged-out users (~5% total). Per T240697.
Perhaps the pervasive use of JS forces people to enable it. I disable it and when things work, they are fast and wonderfully ad-free (or greatly cut down; I do further ad blocking). JS is a security risk IMO.