The point of the Healing Belt, as well as tons of the other cheap items in the MIC was to add depth, variety and choice to the game...Normally pretty much every D&D game ends up the same way...players all get the big 6 and they suck if they dont...It's better to sell everything they find for half price if it gets them that extra +1 on their ring of protection or their cloak of resistance etc... because everything else sux for the price.
The designers and most players agree that the 15-minute adventuring day is very tired. Party wakes up, explores till they have a fight, then they RUSH to the next encounter as fast as they can because their precious buffs are gonna wear our in 5 minutes. As soon as the buffs are gone, they stop and rest till they get their spells back.
The healing belt is a interesting fix for this problem...For an affordable price, and a magic item slot, a low PC can actually have more than 1 fight in a day before needing to rest, or using all of the daily spell resources of another PC to get healed....Oh wait! This fix already exists. Wands of lesser vigor...
If you've experimented with 4th edition, or allowed the Tome of Battle classes or Warlocks or any of the reserve feats in your games then you will have already experienced how much more fun games can be when characters get to participate for bigger portions of gaming sessions. I personally don't have a lot of fun when we do the 1 fight followed by 8 hours of rest thing over and over again.
If you think healing belts are broken, then simply require a 1 hour attunement period before they function. Problem solved.
This. The 15 minute adventure day is a pain. Anything that helps fix it is appreciated in my book. I can't tell you how much it bugs me when I am DMing, and the PC's try feel the need to retreat after every big encounter because they are out of spells/healing, etc. And the same goes when I am a player. I recently created a Mystic Theurge just so I could have a 30 minute adventure instead of 15 minutes...