Imagine a completely new DDO player. They have no past lives. No tomes. No good equipment in the bank. No knowledge of the strengths and weaknesses of various builds. Most, if not all, of the 'power creep' you refer to does not apply to them yet. They are starting the game NOW with roughly the same level of power and content difficulty that they would have encountered say five years ago.
EXCEPT if they happen to choose to make a build that relies heavily on these cool 'active attacks'. As a result, instead of cycling through say four 4d8 attacks every six seconds, they are now getting four 1d8 * 1.3 attacks every six seconds. Their base DPS has dropped from 9.3 to 3.9.
Are there other builds, even other melee/ranged builds, that do NOT get such a significant nerf? Absolutely, but there ARE also going to be some new players who are going to be experiencing the game doing less than half as much damage as they would have before. This WILL make it difficult for some of them to progress.
I do not believe this is a MAJOR issue... but it is also definitely not a NON issue.