The example in the op says nothing about whether it was ever possible to diffuse the bombs in the first place, so it's unclear if there is any element of agency at all, let alone how difficult the scenario is to win if that's even feasible.
Eh, I'd definitely say it's not a "don't ever do this" scenario.
For player agency matters- if luck had been on our side (if I'd rolled a longer fuse, if we'd coordinated better, if I'd gone down instead of up first) then yeah, we could have diffused them.
Regardless, I think it works for the story. First off, it's something I gave myself in my backstory, not something I earned in-game. Secondly, I acknowledged that having this bar to defend was reducing my character's desire to go after the main story line (so I shouldn't have been surprised ;) ). Third, this is intended as a short campaign so I think bigger character's-life-changing events are reasonable if not even expected. And most importantly of course, I trust my DM to make a good story, and he trusts me to help move the story forward in interesting ways. (despite what I said about defending the bar, I can find character reasons to move forward if I need to and have in the past.)
The example in the op says nothing about whether it was ever possible to diffuse the bombs in the first place, so it's unclear if there is any element of agency at all, let alone how difficult the scenario is to win if that's even feasible.
Eh, I'd definitely say it's not a "don't ever do this" scenario. For player agency matters- if luck had been on our side (if I'd rolled a longer fuse, if we'd coordinated better, if I'd gone down instead of up first) then yeah, we could have diffused them. Regardless, I think it works for the story. First off, it's something I gave myself in my backstory, not something I earned in-game. Secondly, I acknowledged that having this bar to defend was reducing my character's desire to go after the main story line (so I shouldn't have been surprised ;) ). Third, this is intended as a short campaign so I think bigger character's-life-changing events are reasonable if not even expected. And most importantly of course, I trust my DM to make a good story, and he trusts me to help move the story forward in interesting ways. (despite what I said about defending the bar, I can find character reasons to move forward if I need to and have in the past.)
If you're having fun, you're having fun. But you provide a lot of context in text that's not in the graphic.