It might not be inflexibility or concealed objectives but the simple mechanisms of weighing up LE priorities and limitations (in terms of man hours/budget/expertise). I can totally understand what Letsencrypt folks are going through after working on my own open source project for the past few years and weighing up my limitations and priorities with what end users' suggestions, requests and enhancements with what they want to see and use.
@NOYB I can understand what you mean by bad vibes in terms of some of their priorities - for me it's not being able for LE end users to change and update their registered LE account email address - although @kelunik is looking at it so I am hopeful Clarify the --email flag requirements? - bare in mind I outlined in detail my rational for my request in that thread so LE folks can see my side. But ultimately, it's up to LE whether or not such requests are taken in. If you follow the LE github issues that are still open and pull requests, you'll see that LE is still pretty much in development so things would need to be prioritized.
Myself, like others probably had a preconceived vision of what Letsencrypt would be when it was first announced and clearly it's this difference in the current LE reality that is what some folks are struggling to accept in it's current form. LE is not perfect but it's still pretty much in development and will eventually evolve and be shaped by end users' experiences, feedback and 3rd party Letsencrypt client developers.