Software engineering isn't about perfection. It's about software that adequately meets the need, which is a lower standard. And cost and time are part of that "adequately meets the need". Perfection would be wonderful, but if it takes forever and costs infinite money, then we're better off with something we can use and afford now. (The rigorous pursuit of perfection, on large systems, means no software, ever. That's not a net win.)
So there's a local maximum in the value curve, between "worthless because it's too buggy" and "worthless because it's not finished". Hitting that sweet spot - or close - is what software engineering is about - delivering software that's actually usable and useful in the real world.
Yeah, but for many things, I don't need it. Do I need a secure word processors? (I mean, yes, in some environments I need a word processor that can operate on classified documents and be guaranteed to not make any copies anywhere else, or make any network connections, or leak in any other way. For most of my life, though, I just need a regular word processor.)
Which brings me back to my point. If I have to get a fully, 100% guaranteed secure (and also crash-proof) word processor, I'm going to be waiting a long time, and it's going to be very expensive. Meanwhile, I've got stuff to write today, and my budget isn't any too fat as it is.
Sometimes fully secure (or man-rated, or 9 nines, or fully validated, or whatever) software is what is needed. Much of the time, though, it's a better engineering trade-off to not go that far.
Software engineering isn't about perfection. It's about software that adequately meets the need, which is a lower standard. And cost and time are part of that "adequately meets the need". Perfection would be wonderful, but if it takes forever and costs infinite money, then we're better off with something we can use and afford now. (The rigorous pursuit of perfection, on large systems, means no software, ever. That's not a net win.)
So there's a local maximum in the value curve, between "worthless because it's too buggy" and "worthless because it's not finished". Hitting that sweet spot - or close - is what software engineering is about - delivering software that's actually usable and useful in the real world.