The whole point of a big set of modifiers is to avoid negotiation. I've talked before about how DCs should be "derived" instead of set. You get the DC out of the situation; the lock is off X quality, the thief has professional tools, they're spending the normal time and making no special provisions for noise or stealth; that should procedurally output a DC the layer can then interact with.
Ideally, that should all be written down, so that once a player has gathered information about the situation, barring anything hidden they didn't get, they can do the derivation themselves, and go in to the action declaration knowing the odds. Success is clear; the lock is open, failure it isn't. In a stress free scenario, we can start applying Take 10/20 rules and possibly just noting the extra time taken. Frankly, I'd prefer players be spending resources in system scenarios to avoid rolling when possible altogether, probably some rogue ability to gain significant bonuses to the roll to overwhelm the RNG to keep pace with similar effects like knock and silence.
The "game" bit is in how players apply that broad palette of actions to get their desired results. The unbounded play, where that goal will change over time and be ones will be set when it succeeds or fails is where the role-playing comes in.