This is true -- as far as it goes. The flavor, however, is that all the Cleric's powers come from his deity. That means that a 10th level cleric has (according to p143 of the DMG and the class abilities of the cleric in PHB) 12-13 powers attributable to his deity, while the Mark of Healing doesn't actually give him any, only augments existing powers (slightly). Even then, the Mark doesn't do jack during the short rests between encounters because few conditions last beyond the encounter.
I don't have time to read through the entire thread, but I just wanted to speak to this.
Flavor is what you make it.
Take a half-elf storm sorcerer with the Mark of Storm. You could choose to look at it as "He could be a storm sorcerer without the Mark of Storm. Therefore, all the mark does is add a touch of wind."
But personally, if I'm playing that character, I look at it completely differently. I say "He's a storm sorcerer
because he has the Mark of Storm. Every power he uses is channeled through his mark - which is also why his powers are greater than those of an unmarked sorcerer. His mark is what lets him touch the storm, and he draws every power through it."
When you look at things this way, you don't NEED multiple feats per mark. Because every thunder or lightning power that the sorcerer gets is a result of his unlocking a new power of his mark. The power of his mark IS growing, every time he gains a new power that it touches.
Essentially, with the old model of the Mark of Healing, you got one extra cure light wounds per day. You use it, and it's done. That's your mark. With the current model, every time you heal (or use the Heal skill to give someone their second wind, if you're not a character with healing powers) you tap into the power of your mark. It's a more pervasive effect. You can choose to say that the cleric's powers all come from his god - I say that when he's HEALING, his powers are at the very least channeled THROUGH his mark. And remember, this is Eberron - so we don't even know if the cleric's god actually exists. While we certainly know that his mark does. In 3E Eberron, we stated that there were many Jorasco adepts who worshipped no god, but drew their divine power from their devotion to healing. I certainly allow this in 4E, personally using the CD feat of the Path of Light for these agnostic healers. They are channeling divine energy through their marks, and can still stagger the undead with this radiant force. But they don't believe that this power comes from a goddess; they believe it is pure lifeforce channeled through their marks.
With that said, a house rule I do use is to allow dragonmarked characters to use the rituals associated with their marks without having to have a ritual book, and having them learn those rituals automatically at the appropriate level. They still have to pay component costs, but the point is that for them, it's not a "ritual" - it's unlocking the power of the mark. In my opinion, the pen-and-paper rituals were developed as a result of copying what the dragonmarks did - that for a long time in Khorvaire, the ONLY way to get
arcane lock was to get someone with the Mark of Warding to perform it for you. if you want to give the marks greater weight, make this the case. As it stands,
Fluid Funds is only usable by characters with the Mark of Warding. What if the same was true of
Arcane Lock and
Eye of Alarm? What if
Secret Page and
Comprehend Language were bound to the Mark of Scribing? If House Jorasco are the ONLY people who can perform Cure Disease, it suddenly becomes very easy to see why they dominate the field... and why, in Eberron, if you need to shake off that sickness NOW, you go to a hospital and not to a temple. If you want a halfway point, keep these chosen rituals open to any character - but double the component cost without the mark. So others CAN cure disease - but it's easy to see why Jorasco dominates the market.
For me, the ritual effects
should be more important than the in-combat effects. The fact that the character with the Mark of Healing can give you a saving throw is a nifty trick. But the fact that he can cure diseases is what keeps him in business... and if you say that he's the ONLY one who can cure disease, then it's huge.
This is too much of a change to the core system for us to put it in the book. But it does give the houses and marks much more weight if you want to do that. Again, if Orien is the ONLY place for teleportation, it's a very handy thing to have an Orien heir in your party.
But the key point is that flavor is what you make of it. When I make a dragonmarked character, i always reflavor the powers to feel connected to the Mark. If someone with the Mark of Warding is using a power that gains a benefit from the mark, then in my mind that power is coming FROM THE MARK.
Oh, tied to this: Something I pushed for that I don't think made it into the final book was to say that dragonmarks still do grow as their power grows... which is to say, as the character gains more powers that benefit from the mark. With that said, they don't have to have a simple three sizes any more. If you look at the pictures and assign a numerical value to each mark:
1. Least
2. Lesser
3. Greater
4. Siberys
... then you could now have a seventh level character with a mark of size 1.7, not quite at the "Lesser" level but moving towards this.
I do this, and as a result when looking at a mark you actually get a greater sense of the character's capabilities. if you see someone with a "greater" dragonmark, you know that they have some very significant power that they can draw through the mark. But again, that power ISN'T three abilities each of which can be used once per day; it probably means that they're high paragon or possibly epic.
Beyond this, there remains the point that marks let you use the dragonmarked focus items that form the backbone of house business - creation forges, speaking stones, and the like.
The core point is a good one, and it was the question we struggled with. In 3E, the Mark of Healing was more useful as a back-up heal for a non-healer than it was for a cleric. The Mark of Making was a better deal for anyone but an artificer. Under the current model, the marks are considerably less useful for the jack-of-all-trades effect - but have a stronger sense of why these houses can dominate a field (especially if you use my restricted ritual access houserule). The key is whether you see the mark as one feat... or if you look at it as being an integral part of each power that it enhances, which is what I do.