I think many of the enhanced abilities that extend duration are built around change in rotations by added new skills. So to attempt to make them more fluid in rotations. For example the duration of the buff from heavy thrust is just about right for the rotation up till you get the buff. At that time I added a few more skills in and was having to clip it to make sure if would last through my rotation. When I had the buffed version, as long as I don't have to mix up my rotation, it flows. So many of these enhanced versions are not necessary at low levels and if were base it wouldn't hurt but not necessary.