This is the reason, i think, corporate world HATES with passion such devs. Even tho they need them to meet deadlines.
It also gives a bit too much power in negotiating to the employee which is also seen as "bad" in corpo.
Which is the right attitude, imho. Even if that person loves the company and would never leave - what if a bus runs them over?
On a large scale, consistency is more important than excellence. You need to be able to plan, "if that guy stays, the project will be done in 4 weeks, but if he leaves, it will take four years" just won't work, because you cannot rely on it. It's much better to be able to say "it will be done in 12-14 weeks" with high confidence. Sure, your whole dev team might get run over and spoil your plans, but that's really a case of force majeur.
Somewhat, yes. You want to be able to plan. Inefficiency is often the price for being able to plan. Since it's often not only about this one project, a higher price is just fine - you may have to coordinate with marketing, legal, sales, manufacturing etc, then the total price will often be so large that the 10x of the software project doesn't really matter, but if it falls flat and gets everything delayed, the damage may be huge (think global launch date missed).