Why isn't there a standard method to convert GFA to JSON? I'm confused why the GFA format doesn't have a standard JSON parser. It appears to be related to a decision made several years ago, here.

The objection appears to be "JSON isn't necessary, as it's just a simple linked list. Users could write their own". However, I would think this is a useful feature. 

There are applications I could think of whereby a JSON would be necessary, or at least very convenient. 

(1) Is there a standard way to convert GFA into JSON? Or do users write their own scripts? 

(2) Is there a conceptual reason why GFA doesn't convert into JSON?
Short answer: no, there isn't a "standard" method, and there won't be.

Long answer: like TAB-delimited and XML, JSON alone is not a specific format. You have to define a schema to give meanings to data. However, unlike TAB-delimited "format" and XML, there is not an official way to define JSON schema. There have been various attempts but all of them are complicated and none of them are widely adopted. As you can't write down a JSON schema for GFA in the first place, there won't be a "standard" way to convert GFA to JSON. The best you can do is to roll out your own in-house solution, unfortunately.