As Clayton Christensen put it, "[D]isruptive innovations ... offered less of what customers in established markets wanted and so could rarely be initially employed there. They offered a different package of attributes valued only in emerging markets remote from, and unimportant to, the mainstream." 
In this case, a serious Unicode font with full TT hinting, all styles/weights, multiple glyph sets is seriously over-serving the needs of the mobile app market. I am currently building a mobile app that uses beautiful typography, and open fonts are working wonderfully for me. I don't need any of the extra font features you mentioned; I don't even need bold and italics versions of my fonts for my apps.
This form of disruption is called "low-end disruption" and "targets customers who do not need the full performance valued by customers at the high end of the market."  Open fonts very much fit that description, and their growth trajectory suggests that they will serve that role well.
Over time, the high-end market players tend to get eaten alive by an innovative low-end disruptor who upgrade their offerings and price points. For examples, see Nucor in steel and Toyota in cars.
 Christensen, Clayton M. (2003). The Innovator's Solution : Creating and Sustaining Successful Growth
I'm having trouble imagining 10 people getting paid $100k/year, working full-time for a year on a font. The Ubuntu font family is a serious font, it includes 13 fonts covering 1200 glyphes and 200-250 languages. It took about a year to develop. While 10 people might have worked on it in total, it would have been done in phases, not 10 people for a full year. Maybe Canonical did pay a million dollars... did they?
edit: Wikipedia also contains this regarding Dalton Maag, the foundry which created the Ubuntu font:
"In July 2012 the Rio 2016 Olympic Games released their brand font created by Dalton Maag. It was based on the letters and numbers within the logo already created by Brazilian design agency, Tátil. The typeface took eight months to create and comprises 5448 characters. The design work was mainly done by Dalton Maag’s Brazilian office, which worked with the London team during the font engineering stage, and also with Brazilian consultant Gustavo Soares, who worked as the technical interface between Dalton Maag and the Rio 2016 team."
There's an example of a typeface built over 8 months using two teams in two countries.