The fighter and the paladin pretty well ganged up on the knight & stole his stuff

[Klaus]

Well, clerics have always been very capable warriors in D&D. In Basic/Expert, they were very close to fighters as far as melee combat was concerned. Their inspiration is generally cited as the religious orders of knighthood such as the Templars, Hospitalers, and Teutonic Knights. The description of the class in all editions has supported the "holy warrior" archetype.

You might introduce a new class called "holy man", but when playing a "cleric" in a game called "Dungeons and Dragons" I expect to be able to strap on some heavy armor and smite evil with a mace.

I hope that the cleric at least loses Heavy Armour Proficiency, keeping it on par with Druids.

 

[Stalker0]

No body wants to play the medic, and WotC making the Cleric a cloistered cleric by default will result in people not playing it. They over-powered it in 3e to con people into playing it, so at the very least they're not going to make it weak.

The reason people don't play a healer is because it consumes:

1) Resources that can be used for awesomeness.
2) Actions that can be used for awesomeness.

It sounds like they are handling both in 4e. There may be ways to heal without actions (or as a consequence of other actions), and it may be possible to do healing without expending so many resources. With that in mind, people may be much more inclined to play a cleric without needing the carrot of an overpowered class.