I remember a PnP game one, we had a huge build up to a dragon encounter... Big Big beast and one we fully expected to loose a couple of characters to. My cleric and a mage teamed up with a "hope for the best" attack where I dumped Harm and hoped to beat his SR (we gave it about a 33% chance) and he would dropped magic missile as each missile got a SR check.
I got through and dropped it to 2 HP instantly and then the Mage's first missile got through on his check and BOOM a 20 and big bad dragon dead in about 5 seconds.
Was it awesome ... well kinda .. but that feeling of that was awesome quickly drained away and in it's wake was disappointment. hell we even asked if we could fight it again (consciously choosing not to use Harm) just to see if we were up to the task. Happy to note we had the **** kicked out of us, my Cleric ended up pretty much naked but we scraped through.
DDO without some boss immunities would be the same, hell it was the same. Kinda cool at first but quickly turning into a big pile of"meh". Now if they were to tweak it a little so that tactics could be used (probably not insta kills though) then I would be OK with that.
Say, for example, that you could trip bosses but they had to fail 4 checks in 5 or 6 seconds, same for CC and once they fell to it it lasted a lot less time. Say 10 seconds max. You would then have to have a party that really coordinated well that could take the boss down without too much damage but then if they are playing together and working together well isn't that a good reward for successful group tactics?
I don't mind the idea of some tactics and CC working in even more limited fashions against bosses but the real bugger is when they have blanket immunity and resistances to everything DPS wise. As a caster I almost always just pike the fight and buff and scroll / spot heal if I can because it's a complete waste of SP. At least if the group seems to have it in hand. Occasionally I have had an intim specced caster and ran in there and pulled agro off the tanks (generally sacrificing myself) so they could get a heal in. As a 10 - 45 second distraction I am generally sill more useful