First off, I think the Incredible is a great phone. Played with one a Verizon rep friend got a few days before launch, and it's the first phone I've picked up since my 3GS that I've actually been envious of. BUT, and it's a bit but, a lot of the points you raise aren't really valid.
Multitasking is an iffy thing, and most users will never take advatage of it and it's a rather large hit on the battery, which people ALREADY have issues with on smartphones with large touchscreens. Power-users will use it, but that's not who Apple is targeting. They're shooting for the middle 90%, because that's where the money is.
Removeable battery would be nice for sure, but as in their MacBook Pro lines, they've demonstrated that sealed units lead to bigger batteries and more durable construction. While I personally would enjoy the removeable battery, I do understand where Apple is coming from.
As for tethering, well, unless you're avoiding the carrier (and you'd have jailbroken and iPhone at that point anyway) you're looking at spending an extra $30/month for the tethering package. There's a reason why it's sold so infrequently; no one takes advantage of it.
The Incredible has better hardware than the 3GS. And I like the OS more, except for the ease and quality of applications available for the iPhone. However, I am not exactly the target for the iPhone, and there will be a new set of hardware coming out in a few months that should (although maybe not, we'll see!) be comperable with anything on the market currently.