The iOS platform isn't exactly friendly with 3rd party browsers. Users are forced to stick with Safari as their main browser. Other browser companies are still releasing their product to iOS, despite their product not being able to be used as a default choice, because they just want to be part of iOS's ecosystem. Right now, Safari dominates 55% of the mobile browser market, while Firefox only holds a measly 1%.
Jay Sullivan, Senior VP of products for Mozilla, and Mike Taylor, a Web Opener for Opera, believe that the consumers' choice in what browser they use is an important part of what makes "browsers, and the Web in general, great." Many companies see the importance of giving consumers a choice in what web browser they can use. Microsoft especially took notice when the EU demanded them to give consumers more web browsers to choose from instead of its Internet Explorer.
Firefox will continue to work to improve its browser on the Android OS, because it allows them to create the browser it wants. However, despite offering its browser on Android OS, many users will still opt for better alternatives like Chrome. If it hopes to grab more of the mobile browser market, it's probably going to have to place all of its bets on its upcoming Firefox OS.