Why Mr. Hobbs, how dear of you to grace us with your presence.

I actually disagree that Atonement goes away from disc, but I'm looking at it over a longer period of time. Depending on when a person started playing a priest their ideas might be different. I think you're right that Atonement goes away from the flavor of disc based on the trends set in Wrath. My perspective starts in early BC as a PvPer though, and thus I think Atonement is perfect for disc. Before Wrath disc had quite a few offensive talents and it was a tree that did a little bit of healing, a little bit of mitigation, and a little bit of damage. Atonement has brought us back to those roots.

I think that Blizzard has still allowed Atonement to be a choice that some priests can use, and some priests can choose not to. I love having the option of both, and I know many priests who do not take the option. You could, can, and (with this change) will still be able to skip those talents and get some really nice holy talents. I personally love having surge of light and Desperate prayer (I only give 1 point to inspiration since my crit levels aren't that reliable for getting the buff up anyway, but 1 point is better than no points.) It doesn't seem like a force to take Atonement, just an option.

I don't think it was terribly implemented either. Every heal in the priest toolbox is situational if you think about it. Holy priests are different, but disc, definitely only uses certain spells for certain types of damage. I guess with Atonement, I think a lot of people don't like it because they wanna put on their healing pants and just want to heal. Most people forget that disc was once a blend of offense and defense. That said, I think finding the right ways to use it takes a bit more thought than just using it as the mana return cooldown it was in beta. That extra throughput is great, and honestly there are a ton of situations where smiting is the best thing to do in a raid encounter because there just isn't enough damage. And every time you help dps, you're helping the raid mana by helping the fight go faster ever so slightly. I like being able to do damage instead of just standing around and recovering mana or casting superfluous heals on people who were already topped off save for those 2 points of HP that the padders want to get. There are so many more lulls in the current content than I think people realize, and everyone of of them is a Smite moment. I like being able to cast all the time. This might not happen as much in 10-man guilds though (i do 25 exclusively) since 2-3 healers have to multitask a bit more.

All I hope right now is that this change to Holy Fire is balanced so it heals more than Greater Heal, so that it it will be balanced to account for less shield HPS (since you won't be getting the effect of Strength of Soul to increase your output.)

As for shield usage, I think the direction they're going in is better than limiting the amount of shields that can go out. Adding a cap like that would have to take into account all the different sizes of groups, and figuring out the magic number is like saying "there is one way to use your shields, and we have decided it is this" it restricts creativity on play styles. There are some fights where I put 10 shields out, but not back to back, just over the span of 30 seconds because I'm saving people who are taking spots of damage and I want to keep them from getting to low, and then letting the raid healers fill them up. I couldn't do that with a cap, but that isn't spam since I'm doing plenty of casting inbetween. A cap is just too restrictive, and this expansion was supposed to be all about having different ways to get to the same goal, both in playstyles and raid strats. Plus, as you said, disc AoE is janky. I don't think a new spell is going to happen any time soon, if at all, so it's important that we be able to use our shields as much as we can, even if there is a price to pay through mana.

Sorry these thoughts are a bit jumbled. I definitely understand people don't like Atonement so for those of you who just wanna heal, heal your hearts out. I just personally love getting back to my old PvP roots =)