It is confusing to users, especially new ones; they may not realise they need to copy the patch to the temporary area first, possibly even inadvertently modifying a patch in ways they did not intend to.
Adding to the confusion, changes saved through the “Save” button do not actually persist after it is turned off (this is a bug Gaia, although the Sound Designer seems to have found a way around it).
On top of that, editing patches other than the temporary one is just not very useful, because you can not hear what you’re doing. There are some scenarios imaginable, e.g. when you want to make a specific tweak in offline mode, or you don’t want to overwrite your current temporary patch. However these are exceptions to the rule.