Correct.
Actually, I play 1E.
Correct.
Because any published module will assume the party is at full health, ergo all encounters will be balanced for a party with access to all spells and at full hit points. Any party NOT using fast healing and at will magic will be at a distinct disadvantage. Pre 4e, and especially pre 3e (wands of clw) no such assumption was made.
Remember that whole section I talked about having the GM know the consequences for lowering the natural healing rate, well there you go. You just showed why it works!
If you force your party to have slower natural healing, they will be at a disadvantage. Now as the GM, you can either let your party go through the module slower and ahve the party take more rests, or you can add extra healing potions to the loot. It really isn't that hard to accomodate your playstyle with the fast healing as the default option.