As far as shaking your head, I don't see you pushing a better plan ... maybe they should continue with BB OS? HA. Maybe they should develop a new OS? HA. This is their only option.
The problem is that back when Blackberry were big they had few competitors. BBM was one of the few services which could be used internal-only, and MDM was non-existent on most other vendors or operating systems.
Sorry, but to my eyes, if Blackberry made this their business then they would go out of business. A lot of the people who used to have the displeasure of managing this stuff don't want it back, and they will fight tooth and nail to keep that from happening.
I've literally seen wine opened when BES was removed once and for all.
PS - We no longer do MDM since users BYOD, all we have the ability to do is remove the company's Exchange archive (like deleting a PST on a PC). Plus it is encrypted anyway, so if they cannot login then they cannot review it.
For games... sure android and iphones are great but some of us dont use these devices as toys
iPhones and to a lesser extent Androids are ubiquitous now in the enterprise. So unless you think people who work there in are just using their phones for games then I would be taking your statement with a grain of salt. I work for an enterprise (market cap 50 billion) and our tens of thousands of employees all use iPhones.