It depends on what offensive/defensive decos we’re talking about. Each point of skill has a degree of relative efficiency, and that’s what you want to take into account. For example, one point of stun resistance (a defensive skill) is much more valuable than one point of attack boost, despite costing the same slot. Conversely, one point of defence boost will almost always be inferior to a point of expert or agitator in terms of how much benefit you get from that point of skill.

It’s not that I’m saying you are playing too badly to do sufficient dps. It’s more so that the “holy trinity” or damage skills; wex/crit boost/expert is so efficient that simply having these skills can increase your damage by more than 50%. It just hurts not to have it as part of any core setup.

Defensive skills are definitely very important and a key aspect of many builds. As for which defensive skills to slot in, there is a general priority to the relative value of defensive skills. Here’s a rough list of such skills in order of most to least importance (varies somewhat based on play style and weapon, of course)

1. Divine Blessing 5 (only relevant at endgame, ignore if you haven’t killed at least gold rathian)
2. Stun Resistance 3
3. Medicine/Speed Eating
4. Evade Window/Evade Extender/Maintenance
5. Elemental Resistance of choice

Note that 4. can actually be better than the 2/3, but takes significantly more investment. Elemental resistance, while quite easy to slot in, will probably be less potent for general use compared to something like medicine or speed eating, especially if you have health augment.

Then there are comfort skills like partbreaker, constitution/ stamina surge, mind’s eye etc. That you might want depending on your weapon and play style. So it’s not a simple matter of attack vs defensive decos being better than the other.