I always spend FAR too much on this:
I have created a mix and exported it as an audio file, and now I need to cut the start and create a fade in the end. That’s easy enough!
After that I will hit Control+B and bounce the audio file and C12 asks me if I want to replace the event, and yes!!! That’s what I want but I want more! I want it to replace the old audio file with my new trimmed version, why can’t I do that???
I will accept a warning telling me that I alter the file, and all that, but why do I have to rename the new file C12 creates - “filename-01” to what I want, instead of having C12 doing the renaming process?
Couldn’t we have an “update file” command??? Please!
Not to be a smarty pants, but why don’t you make the cut and the fade (e.g. with volume automation) before the export??
I think because Cubase has the principle of working non-destructively with audio (for most cases), this is a design choice, so you can always go back. For more “destructive “ editing where you replace the file on save you would usually use a wave editor like wavelab or audacity.
Because I have to be sure Cubase starts a little because of my servers involved. Always a little unsure especially if some of the tracks has a negative delay.
I could create a fade before exporting, just isn’t the way I do it.
I fully respect that Cubase will protect me against my self 
But I DON’T want to be protected I just want a fast and efficient workflow, and that does not involve to launch my Wavelab Pro to make a trimmed version!