Thanks for your post.
The behaviour you see is by design- if you could change variables and re-deploy the same release you have no way of knowing what was actually deployed based on the version number. Releases, once created, cannot be changed. This is to provide you with reliable knowledge of what a given version contained.
Having said that, if it's something a lot of users don't like we could probably look in to changing the behaviour- please suggest it on our Uservoice
site so we can see if it gets a lot of votes?