I have been packing my PVA bags exactly like this for a good few decades now and I have caught 100's of carp using them when an ordinary rig stood no chance.
The great thing about them is they get the bait down to where it matters and set the trap correctly. A good tip when casting them out is to always trap the line and feel them down. This way you know the lead will have hit bottom first followed by the bag giving you the right lay.
Packing a bag like this protects the hook ensuring it's sitting right and unhindered by any debris which again is important as you don't want to sit there wondering if it's all ok.
It's important when fishing to have confidence in what you are doing and using a bag like this gives you that.