Ideally, they would be introduced with some presence in a novel, an adventure, and a fluff book. Give people examples to love and examples to hate rather than just drop it in their lap and stare at them waiting for magic to happen.
Well, Runecutter's Ruin features a runepriest.
As for the class itself, I personally love my dwarven wrathful hammer runepriest, though to be fair, he only hit level 3 at the end of the last session. So far, in our party consisting of fighter, pally, ranger, mage (charm) and myself, he has been highly effective. He is almost on par with the ranger in terms of damage (though I think that has as much to do with feat/power choice as anything), and he provides enough bonuses and healing to keep the party going.
That being said, I do agree that there are plenty of problems with the class:
The Name: I think a lot of people focus on the "priest" part of the class name and that has a lead to a lot of comparisons to the cleric. Add to the fact that they get auto-training in religion (despite no other reason to boost Int) and it becomes even easier to relate them to the cleric. Simply calling them runelords, runecasters, runemasters, etc. may have eliminated a lot of this discussion.
The Feats: I too agree that the rune feats are bad (to an extent). IF you take most/all of them, they are pretty good. Heck, even rune of eloquence will essentially make you trained + focused on those skills if you take them all. The problem with the feats though is that by themselves, they really don't do anything. Compare this to any other class based feats and I think they'll come out pretty poor. Sure, adding THP to your rune of mending is nice, but you have to wait until at least level 4 before you get even a decent amount of THPs (and that assumes you are not taking Expertise, DWT/Proficiency, or an armor prof., etc. Personally, I haven't decided whether or not I'll take them. In my mind, a feat should be useful the moment you take it, rather than having to wait for 2, 4, 6 or even more levels for the feat to become useful. Adding a single THP to your rune of mending really doesn't do much, even if adding 4 - 8 later on will. This is particularly problematic for those of us who play at most every other week for 4 hours at a time, meaning that we're talking about waiting perhaps 6 months or more before the feat really becomes decent. Perhaps if the feats were more along the lines of "Add 3 + rune feats, max X" they'd be more useful.
The Fiddly Bits: Personally, I don't mind this. The tactician in me loves being able to find the right bonus at the right time. However, it is difficult to keep track of all of it without the use of cards, markers, tents, etc. I figured that out right away fortunately but its still an issue. Doesn't make the class any less effective, but it does likely turn it off to a number of players. The other side effect of this is that if the player of the runepriest happens to miss a session, it may be really difficult for another player to run it by proxy. "I swing my Mordenkrad!" became the default line when I missed a session.
Ritual Caster: I'm not convinced that they need ritual casting to be a good choice. However, I do think that allowing them to cast Enchant Magic Item and/or Disenchant would fit very well into the theme of the class, without stepping on the toes of the classes that get ritual caster for free. Of course, with the Essentials version of item distribution/creation, this would now be less of an issue as Enchant is a lot less useful now.
Those problems aside, I do think that the class brings a lot to the table. Good damage, plus good buffing/debuffing plus excellent versatility is a great combination in my book. Even the poor class-specific feat selection has its own "appeal". Given how tight feat slots often are, the lack of good class based feats (assuming you don't go nearly all in) opens the door for a lot of other feats that might not otherwise get as much attention. I'm seriously considering taking "Shield the Fallen" for instance which I have yet to see another dwarf take in any game. Situational feats often tend to be less optimal because there are a sufficient number of good all around feats to take, but I think there is more possibility here with the runepriest. Of course, this doesn't make up for the poor design in the class feats to begin with.
The other problems (lack of pp's, powers, etc.) are really more an issue with the lack of supplements than the class itself. Compare the number of powers to the number available to the fighter when PHB1 first came out. Simply supporting the class will go a long way toward making the class better and more popular. Another Mastery option would be great, another PP, etc. In my mind, there isn't anything wrong for the most part with the actual powers and pp's, available now, just that by comparison to other classes, they are lacking in options by virtue of being late to the game and not having had any additional support thrown their way.
All in all, I do think its a great class mechanically that just needs some love in order to really shine. It may not have a great theme for some people (and again, putting "priest" in the class name I think is contributing to this), but frankly 4e suffers from lack of flavor in many parts of the game. Even the 4e cleric doesn't really feel like the "old school" D&D cleric imo. The 4e cleric really shouldn't be up front all that much (though I have yet to see a warpriest in action). Strength clerics just were not good enough (imo) to thrive up front and if you weren't Str-based, you had no business being up front to begin with. At the end of the day, I really hope I get to keep playing my runpriest because he is a blast to play. The only thing that seems likely to stop that is death or the campaign fizzling.