What happened in Dorne was meant to show that the people of Dorne had turned on Doran already, that's why Ellaria says "you don't know your own people, their disgust for you, Ellia Martell raped and murdered and you did nothing, Oberyn Martell butchered and you did nothing" while his guards looked on implying that it was a staged coup. It wasn't lazy writing, you just didn't pick up on what was going on.
As for Roose, I think his death could've been handled better, but he's never been seen travelling with multiple guards, plus he didn't know Walda was going to have the baby at that moment, their meeting was interrupted to tell him that.
My biggest gripe with Dorne (and I'll just stick to episode 1 bc I hated everything about last season) is that we haven't seen or heard anything from the people. The only indication is what comes out of Ellaria's mouth and the guards not reacting when Doran died. It comes off as lazy writing to me.
My other minor gripe is I feel like they've completely missed a chance to show the people and land of Dorne. Everything we've seen took place in the water gardens. No towns, taverns, whore houses, anything. After hearing so much about Dorne and it's culture, we've seen jack shyt outside those walls. It's been an overall disappointment and I hate everything about it.