So there's a kerfuffle about addons and healing again. Codi at MoarHPS started it, and then the ever-awesome Righteous Orbs team chimed in. So here's my thoughts, numbered for your convience...
1. Addons are tools. I can do basic math without a calculator. Heck, I can graph trigonometric functions on the x-y plane without a calculator. But it's much easier with one, so why would I do it without one unless I had to? If you prefer to not use a calculator, fine. I've raid-healed without vuhdo, and well, you can have my graphing calculator when you pull it out of my cold dead hands. Seriously. I love that thing.
2. Different people need information shown to them in different ways. For some people, I have no doubt that the default ui is great. But it does not work well and is not efficient for a great many people. This does NOT make them poor healers. It means that *gasp!* the default ui is not one size fits all.
Now, I don't advocate being completely reliant on addons to the point where you can't heal without them. We've all had patch days where everything was borked and it was ack. The key to using addons sucessfully, imho, is to be able to cope without them when needed.
If vuhdo fails me, I know to go find some mouseover macros for pw:s and flash heal, fiddle with the default raid frames (or enable the shadowed unit frames ones if that addon's still working), and get ready to pay more attention to debuffs and prayer of mending than I generally do. I also know to lay in some migraine meds, cause I will have one after 4 hours of raid healing with the default ui. As far as tank-healing, well I don't actually really use Vuhdo for that. I have the tank as my target and penance, greater heal, and pw:s are all keybound.
Honestly, I feel that a healer using addons can be superior to one without addons. We've taken the time to figure out what's important for our healing style and made changes to emphasize the important things (like hots for a druid or weakened soul for me or the time left on beacon or earth shield). But for the most part, I think it's like this...
Imagine two knitters, both about to make the same intricate lace project. One researches yarn, experiments with different kinds of needles, and spends a great deal of time making sure she has the best tools for the project possible. She swatches, makes sure she can perform all the necessary stitches with ease, and lays in a supply of lifelines. The other grabs yarn and needles from her stash (a stash is the yarn knitters have lying around for future projects) and gets started. Both projects will likely end up being beautiful, and the outside observer will likely never know who had the easier time of it, but one knitter did. The prepared knitter. Now, Codi might argue that she's the prepared knitter, and I'd argue I am, but in the end, it only matters to us. The rest of the world sees two beautiful lace items.
In other words, if you manage to get the job done and done well, you're a good healer. The tools you choose to use to get the job done are nowhere near as important as getting the job done.