I'm going to try and be a little more objective but I do have to agree with you. Though serious cracks in the Democratic coalition were glaringly obvious and larger than in the GOP convention you didn't get the feeling of many coalitions falling apart as you did during the GOP convention. To be honest most of the speeches were boiler plate throwing out red meat.
The Dems did start theirs with far, far greater star power than the GOP did and that was significant. I agree that Warren's speech was disappointing. Long on rhetoric and short on fact or policy. Cory, to use a NASCAR phrase, hit his points and delivered and made substantive comments and got the crowed warmed up. Michelle Obama gave a damned good speech but Bernie was unquestionably the star of the night. He hit all the marks right. He urged his delegates to vote for him during the role call vote. Not because it would do anything for Bernie so much as it would keep the impetus on key aspects of his movement. The fact that the platform committee made some serious concessions to Sanders supporters was significant too. They have succeeded in pulling Hillary farther to the left than where she would probably like to be. Bernie also made a very good point to his supporters about it not being about him but about the movement they have started for Government reform.
So yea Bernie crushed it last night. If Bernie lets it go there and that's his last hurrah for this election season then it may not make much of a difference now. If, however, Bernie hits the campaign trail as a surrogate for Clinton and passionately advocates the progressive issues that Clinton has agreed too than Bernie would be a very potent surrogate for Mrs. Clinton. That would bring up the question though of "If Bernie does that, what's in it for him?". I would imagine that if Bernie actively campaigns for Clinton, as she did for Obama, then she will probably nominate him for a cabinet position.
All in all I think last night was a good night for the Dems. I think Bernie did an outstanding job of defining why his supporters should support Clinton over Trump and I think he was affective in persuading many of the Bernie Bros to stop crying and do that.
What was most significant to me was the level of star power on the Dems first night vs. the GOP's first night. This tells me that Clinton has a big advantage in surrogates who will campaign with and for her. Corry Booker, Barry and Michelle Obama, Bill, Sen. Warren, Bernie, The Bidens, etc. Where as the GOP on their first night has a bunch of C list has been hack actors and government officials no one had heard of. That was really quite telling.