Kits were balanced to exotics so that they would have the correct damage.
Then ascended weapons were introduced.
With ascended weapons in the game the playing field has changed and now kits are no longer functioning at the correct damage level.
this issue will affect the bundles of several classes, but especially the engineers who use kits instead of weapons (as their weapon selection is tiny and the weapons are fairly niche/rubbish as well)
The pertinent question is: have the devs given any indication of when they are going to fix this.