I recommend you to read this post [Edit: Added link to “Why I think Fairphone OS should drop root and pre-install Google Apps” by @ben] and the following (lengthy - you might want to summarize the topic) discussion. It’s a weekend read because it goes quite deep and has a lot of background information. Very interesting are also the posts by Fairphone’s former lead developer @keesj (filter out his posts by clicking this avatar and choosing “8 posts in topic”).
It’s good to keep this in mind always. I can understand well that Fairphone’s priority is to ship security fixes to the highest relative amount of their customers so that as many people as possible benefit from them as soon as possible. Maybe it’s a wrong suggestion, but I’d even go so far as to say that the 5% FPOOS users are more security aware than the 95% and can be “entrusted” with security wholes for a longer time, until they receive the fixes.