Ghostcrawler, in his post on Stats on Gear, talks a bit about holy paladins:
I mentioned two out of three paladin specs above. That third spec has been a thorn in our side for a long time. Paladins in general have a knack for that. I kid. (Mostly.)
Heh. I'm pretty sure we're all down with this. Ghostcrawler goes on to say:
I'm talking about Intellect plate. We don't like Intellect plate, but we haven’t come up with a good alternative for it. The pitches we hear most often have downsides we don't like. Yes, a Holy paladin could wear mail… at which point their silhouette would look a lot like a shaman instead of a paladin. Yes, Holy paladins could derive their spell power from Strength… at which point they also hit with their weapons nearly as hard as Ret paladins. Yes, we could convert all that Strength to spell power, and convert the Hit to Spirit and the Expertise to Mastery or whatever. The Spirit to Hit conversion does the job, but it's not super elegant or intuitive. I’m not sure we want to pile more onto that design.
I like Intellect plate. I'm really happy that the devs have refrained from expecting Holy paladins to wear mail. To me, it's one of the iconic elements of the class. Paladins wear plate. I played through the times where Holy Paladins would dress in cloth, and they were terrible.
As for wearing Strength plate, in my mind the real problem with that solution is the non-armor item slots like rings and weapons. Right now, holy paladins have their own armor and share the non-armor slots with the other healers. If we were expected to wear Strength plate, would we also wear Strength rings and use DPS weapons? Or would we wear Strength plate but Intellect rings? Or would we become the new hunters, and simply roll on everything.
It sounds a loot more complicated than the current system. The current system is simple. You're a paladin so you wear plate. You're a healer so you go for Intellect and Spirit. That's pretty much all you need to know to get a good start gearing your Holy paladin.
Intellect plate isn't ideal. But I think it's the most workable solution. Between the larger amounts of loot dropping from bosses, tier tokens, and vendor items, I think that having Intellect plate isn't too much of an inconvenience.
Now, if only Blizz would make a two-handed healing mace with Intellect and Spirit.