I think it all depends how you cook and eat your fish.
We tend to cook and eat our fish skins, bones, fins all in ( don't ask but we do). If we don't bleed the fish, the blood will tend to stay around the cavity behind the guts area, and it doesn't taste very nice when cook.
If all you do if fillet the fish avoiding the bone areas, there wouldn't be much blood in the flesh ( you can still see the blood vessels and all but wouldn't taste much different).
The only exception is for large mackeral and scats which we want to turn into sushi then you want to bleed the fish, you don't want blood in the flesh