4th Edition made a great Paladin...

[Schmoe]

Divine Challenge damage is small, yes- but at what point does a fighter's OA against a marked enemy start doing the same amount of damage on average? They both have the same "-2 to hit anybody but me" effect to discourage enemies from swinging elsewhere, and radiant damage resistance isn't nearly as common as radiant vulnerability.

In addition, it's inescapable damage. A DC'd minion either goes for the paladin or does nothing, because attacking anybody else is literal suicide. The paladin might not be able to lock down a lot of enemies at once with any particular ease, but he can ensure that any one minion never, ever attacks anybody but him.

I agree with you here. D&D isn't World of Warcraft. Defenders aren't supposed to have a fool-proof threat mechanic, they are supposed to have tools to make them more attractive targets, in addition to the tactical positioning and maneuvers that they used in previous additions. A paladin will do a better job at protecting the casters than a rogue, and that's the point.

I don't see much to worry about in terms of MAD. The paladin needs either Strength or Charisma, and then Wisdom. Dex and Intelligence are useless aside from Reflex defenses- which are boosted by a paladin's shield- and Constitution is something I'd cheerfully leave at 10. There's a reason a paladin starts with more base healing surges than anyone else.

Here I disagree. I fail to see how someone can build an effective paladin if he prioritizes STR->WIS->CHA. I could see CHA->WIS->STR, CHA->STR->WIS, or STR->CHA->WIS, but if you go with Strength first, I think you have to go with Charisma second, or you will simply be too limited.

 

[jensun]

The paladin requires decent Constitution to fulfil his role but has to split his ability points between three other stats.

You are completely overrating the importance of constitution for defenders.

The difference in total HP is very small and the extra healing surges can be compensated for by a single feat.

While it may seem a bit odd Con can easily be left at 10 or 12 as a Paladin, especially as you start with Plate armour proficiency and a bucket load of Healing Surges.

 

[Wormwood]

While it may seem a bit odd Con can easily be left at 10 or 12 as a Paladin, especially as you start with Plate armour proficiency and a bucket load of Healing Surges.

This.