[Retra]

You can consider that a positive, but it is also an inevitability. Nobody is talking about immortality here. But you also wouldn't be saying the end of all life would be positive (which you could, for exactly the same reasons) and that still wouldn't mean you shouldn't delay it for as long as possible.

>almost everything we enjoy about life may be because of our mortality

You don't know that you're mortal until you die. It makes no difference here, because even if this were true, you are already assuming you are mortal regardless of the facts, and you will continue to do so. Being immortal doesn't imply you've also reached some state of deep enlightenment about it.

Besides, you can invert this just as well: everything we enjoy about life may be dependent upon the belief that we're not going to die soon.