What would be the current liability for LE to support the scenarios listed in the cons? I suppose if something bad does happen later on for the more complicated/risky/uncommon scenarios that are harder and more complex to support, it would burden and harm the reputation of LE, so considering the early stage of the project, and as a user who can already benefit from automated 90-day certs, I would rather have them focus on making the existing policy as solid as possible (and not winning over existing customers of paid certs)
In the mean time, the respective niche communities can still work with LE to explore ways to utilize/automate the existing process, until it improves to the point when supporting non-mainstream devices is deemed not so risky and can be done with minimal burden to LE.
In summary, longer duration certs (for the convenience of supporting a wide range of uncommon scenarios, e.g. non-webservers with limited exposure to internet) should have lower priority given early stage of the project.