Suggestion: Giving more 'Revealed'
I think this change might be acceptable, but only if they reworked Thieves to be less reliant on the stealth mechanic. With the Acrobatics trait line getting nerfed in the recent patch, Thieves are more dependent upon stealth as their primary means of damage “mitigation” than ever (it’s still possible to hit them in stealth). Giving everyone ready access to revealed without any other changes would just be a direct nerf and do little to improve game balance or build variety for Thieves. Although stealth suffers from limited counterplay, Thieves are currently in a place where a major nerf to stealth (in the form of added counterplay) would just break the class in competitive settings and remove one of their major tools for disengaging.
Mesmers would likely be less impacted by your proposal, since most of their builds don’t really rely entirely on stealth for survivability. However, that’s not to say that they wouldn’t be affected at all, and I think all of the professions with access to skills that grant stealth would need to be looked at before implementing the change.