I understand your perspective and it is likely to be the same as most of those who turn to MAIB as a mail solution.
Our corporate mail requires all those sort of assets and is not my responsibility or concern.
To give you, and possibly others, some idea of my perspective/involvement:
I am working on a client’s project.
They have no interest in Roundcube, ownCloud, or any fancy user interface with their mail server. All they want is an owned, core, secure, simple to maintain, lightweight, backend to very small, multiple mail accounts. They will only be dealing with small emails, mostly in plain text, with no attachments. They require spam filtering and are expecting, who doesn’t, to get a fair amount of that. They require no backup of email. but do require system backup and updates. They expect a ratio of about 15:1 of genuine traffic in:out.
MIAB appeared to be the easy option for me and them. All their interaction with the backend will be through their web site and their own interface.
MIAB has been a very simple install from my perspective and literally only a few hours from install to working system (LOTS of praise to the team for that!) I now need to just clip its wings and fix some inter-operability issues.
Thanks once again