These decisions happen all the time by people with a C in their title that because they don't know tech but still fall for the snake oil salesmen's pitch.
I see where you are coming from and I would (wholeheartedly) agree that even in the real world inefficient, corrupt and downright stupid systems can persist for quite some time, be it by inertia, shortsightedness and something akin to institutional tradition. Or fear to change a (hardly) running system. I also understand the `too big to fail` route, especially when it comes to bad guys.
But there are three types of people at meetings such as the fateful one with de la Mar. Strategists, lawyers and bean counters. And not having at least one bean counter perk up and ask about something as obvious as `
so, about these maintainance costs?`
That would be too much for my group.
If it were something subtle, something requiring lateral thinking, maybe we could swallow it. But this is too basic. And it is in a way too sensitive area, requiring way too much investment. Hosts are where all the dirt is buried. Hosts are where business is done. They are the source of power.
If the corps would be bumbling buffoons at even their core competencies the next thing my players would ask me would be how these frags even became the Top Ten.
I am not trying to convince you that you´re doing it wrong. Whatever works for you is fine. But I don´t see your approach reflected in a lot of canon sources. Maybe that is what bothers me the most with the `deadly hosts.` It is not in line with the rest of the worldbuilding. The corps may be portrayed as uncaring, soulless and oppressive, but never as comically stupid and gullible as this. It sticks out like a sore thumb.
'The Hosts grew sentient and went to war with the Monads, so we blew it all up and tried again, with less success'. 
Actually I would prefer that to what we have right now. (don´t forget to shoehorn the nulls into it somehow.) Also, one can only hope for an end to the strained effort for complete matrix/magic symmetry. It robs both of flavour.