I personally want addons and macros. and HELL yes on the customizable UI and mouseover abilities.
In wow (yes, I realize some of you idiots will look down on me for that) the main macros I used were for different mounts, or in a few cases, use of an item/trinket before a cast. My shaman for instance, was an engineer, and thus, had an On Use ability he'd added to his gloves. This meant clicking the glove would give him a stat boost for a short bit. What I did was macro that to one of his abilities.
/use <whatever number counted as gloves, I'm not at home now>
/cast Lava Burst.
this kept me from having to add yet ANOTHER button on my bars for an item.
In this game, I'd be doing it with some of the relics I've seen. On use Alacrity or such.
Another thing my priest had, was
/cast @focus Pain Suppression
Pain suppression was an ability that reduced damage taken for a short period of time, on about a 2-3 minute CD. By doing @focus, I could have the main tank focused, and it didn't matter who I had targeted when that Oh crap moment came, I could hit that button and be sure to hit the right person, instead of trying to find the tank in the list of raid member.s
Its been since the end of vanilla since you could actually macro everything into one button. Originally, yes, a warrior could have ONE button on his bar and it'd go down the list, if something wasn't available, it'd hit the next one. Guess what. blizzard blocked that. And any sane Bioware dev would, as well. NOONE is asking for that. Hell, you don't even need a /castsequence ability, if you want to keep the one button macros gone. (In wrath, a paladin tank could macro his rotation to 2 buttons easily)
But, so far, I haven't seen any class with a ROTATION, its all priority based, with procs. This makes the 1 button macros break if you set up the API correctly.
Another great thing: Macro your CC button to say "CCing %target, marked with %mark". This way, if you have 2-3 ccs going off, you don't have two of them hit the same target and waste a CD.
As far as addons, I'd love Power Auras/dot timers. Getting into flashpoints with 2-3 sorcerors, its a PITA to figure out which one of the 2-3 Afflictions listed is mine. In fact, there is NO means of seeing such by the UI currently (or if so, i haven't found it). One of the things i had in WoW was a hud, that included the debuffs on my target, with mine in a larger size, so I actually had a means of seeing which ones were mine. Dot timers would do this just fine as well.
Currently as a Sorc, in any aoe situtation, you almost have to watch your bars/buffs constantly hoping for a Lightning storm proc. More than once I've looked back up to see how things were going, and when I looked back, I'd missed almost half of the buff time.
I also customized my UI. Sorry, I realize some of you like it as is. I don't. to me, its meh at the VERY best. I don't need to see my unit frame portrait, nor my enemies. Its one thing I removed in wow. I WOULD like the ability to move everything, resize some of it, etc. And yes, I'd prefer ADDONS than just Bioware options. Why? Because I've yet to see a game company come up with all the options fans want. Ever.
Damage meters, While yes, I'd like them, having them only show ME would be acceptable, or having the entire thing only viewable by OPS leaders.
Some people say "just do the flashpoint multiple times, with different rotations, see which works". But unless NOONE in your group got any upgrades, or changed THEIR rotation, this doesn't work. You can't tell which was YOUR dps changing it, or your teammates.
And to those who just say "just have fun". This IS fun. Customizing my UI, figuring out my priority list/rotation, etc, THAT is fun. Having to do extra clicks on things that make no sense...is just asking for carpal tunnel.
I did play in vanilla wow. You know why raids were hard then? Not because of encounter design. Because of ****** tools. So, people made addons, some of which completely trivialized content, but most of those were broken (the original decursive just required mousing over icons, no clicking required. that got broken. As did the healing mods that auto-chose the best heal.) Bioware can do much to learn from blizzard and block the stupid addons to begin with by limiting the API, while letting those that do no harm with no issue. Its always possible to block something else later, but limiting us to being unable to change things or actually ENJOY healing (I agree with so many posts about the mouseover bit), makes this game a lot less fun.
Sorry I'm not a masochist like some of you.