The basic answer is:
Some people used forced de-target skills, such as flop and hips, to exploit instances and cheap out large portions of them, or even cheat through boss fights entirely. Turbine's response was to disable those skills that were the biggest or most common lynch-pin to the exploits, from being used i those locations. As a result, the rest of us are now no longer allowed to use those skills for the reasons and in the manners that they were originally intended to be used, in perfectly legitimate circumstances.
This is why we can't have nice things.
This is why Igash lost his fancy throne,
This is why some amusing or technically impressive visual effects have been cut out of some boss fights in the past, and can now no longer be seen.
Don't exploit instances, kids.
On the flip side, if turbine are wondering why there has been a monumental increase in the amount of instance exploiting going on, and why more and more people are dedicating themselves to finding ways to skip through your newest content - It's because of the way it's designed. the amount of repetition needed,coupled with how long you've made various parts of the instances or fights take is precisely what is driving more and more players to look for ways to skip it. If each minor pull takes three or four minutes just by virtue of the creature morale totals and other ancillary effects, and you have a dozen or more of those pulls in an instance... and Virtually Nothing Else, people are not going to be interested in repeating it a dozen or more times, and they will inevitably look for ways to skip what parts of it they can.
Both sides share a portion of the blame on this, but since no amount of community calling will stop people from being people, turbine are the only ones with any real power to fix the issue.
Rider, Fighter, Virgin, Lover; Watcher, Chaser, Bearer of Pain.
Victim tormented, Abused and Broken; Rise from the ashes and Hunt once again.
And Vengeance Be Thy Oath.