...with a huge army of engineers who can do basic admin jobs on it because of the AD integration...with a full suite of structured training programmes to bring up more of those engineers and keep them current.

I suppose if, as has been my experience, “feature complete” actually means “whatever features ship with Exchange” then you’re right. But isn’t that the tautology of enterprise software? Vendors build a moat of features which end up in enterprise RFPs and ultimately lock out other vendors - not because the features are necessary or even useful, but just because they exist and, perhaps, some department head thinks it might be useful one day - or, more likely in my experience, the consulting firm involved in procurement gets a cut of the action. Having been on both sides of this process, I know exactly how it works in practice.

So I’m sure that for some huge enterprises, the complete feature set from Exchange is actually necessary, or at least desirable. But for everyone else - including many companies I’ve worked in at a senior level, and almost certainly many of the victims of this vulnerability - I’d call shenanigans right back at you.

Feature completeness doesn't mean the software is better. I think, many of those companies affected or the poor people there certainly wished for at least a moment they didn't use Exchange.

It’s pretty bad, but it’s probably the best of the available tools at the time. Serious competitors like Groupwise and Lotus were kind of nightmares. Open source alternatives offered great individual components, but not the integrated solution you got with Exchange/Outlook/Sharepoint.

Sometimes being the least worst option is all it takes.