I mean, technically, negotiations were possible, with Eshonai & a changing Dalinar, but with the info they had, they were stuck between a rock & a hard place (I'm never using this turn of phrase again, it sounds so stupid) Eshonai was a really, really good person but Venli's actions were more realistic, her anger made sense, she was responding to her people's genocide, which truly was a game to the Alethi. Yes, she didn't really know what the Forms of Power would unleash but the warnings were there in their Songs of Remembrance but what other options did they have? They were getting out of options to even reliably feed themselves, completely dependent on the Gemhearts they were getting from the Chasmfiends. So, yeah, agreed.