"if you want to run linux on a phone"[sic] ... assumes a goal (on the part of the developers). What if the goal of these developers is to demonstrate that they are up to the challenge presented by Apple ... to show that some people will overcome the deliberate impediments to alternatives that companies like Apple place in their way? Putting their effort into a more open platform wouldn't serve that purpose at all.
The other fallacy is one we commonly hear in the open source is that the time some (usually smaller) group of people spends on some alternative project (whichever project the commentator thinks of as unworthy of the effort) is somehow "wasted."
This has always boomed with the arrogance of ignorance to me. Who are these people, on the sidelines, to declare how anyone else should use (or "waste") their time.