This should not be implemented as it will result in “elitist” behaviour with any sort of group activity and encourage discrimination against sections of the community who do not have the “expected” setup.
As an example someone might want to speed run dungeons, and have it in their mind that only people setup for DPS can do speed runs efficiently so will start inspecting anyone who wants to join the party to see if they have a class cannon build or not, and remove anyone who does not.
Also, how far do you take a system like this, just armour, jewels, weapons, what about traits and skills? Implementing a partial inspect system will result in some vocal members wanting more information from the inspection.
Guild Wars 2 is about, using ArenaNet’s own mantra, playing the game the way you want, this include armour setup, weapons, jewels, traits and skills. Allowing an inspection tool would ultimately result in a reduction of variety in player builds as people will standardise their builds to what groups expect them to have.