why? you are presented with a choices where you either live forever as an AI and give the body to Johnny, or take the body and live another 6 months.. (remember, you were shot to the head originally... you are living on borrowed time anyway...)
You're an engram in Cyberspace and you could be gobbled up by AI Alt whenever she wants, or get attacked by the monsters behind the Blackwall.
In the prologue your life was ripped from you by events beyond your control - first taking away control from the player and then saying "you live on borrowed time", as if all the fuckups were somehow V's fault, is bad writing.
Dex fails to properly vet Evelyn
T-Bug loses track of Yorinobu
Saburo and Yorinobu have their family feud at exactly the same hour as the heist
Adam Smasher one-shots you if you don't hide
You can't fight Dex's bodyguard as in the trailers
You can't decide if you want to plug the chip in your head or not
And so on...
Other posters already debunked the "Bittersweet" theory several days ago.