I think it depends on what you do for work. I'm not going to ask an agent to book my flight for my vacation to French Polynesia. I want to pick my seat and potentially find a deal making an upgrade worth it, choose an airline, etc.
But my routine business trips in the CONUS with strictly defined booking options... let me just email an agent "Get there by meeting on day A, leave after meeting day B" and have it sort it all out without the drudgery of the corporate travel portal. YES PLEASE!
A good agent would call you to ask clarifying questions and then actually get you that perfect seat, etc. ideally
By that point, you don't need an AI that boils the oceans and hopefully doesn't confabulate or misinterpret your words, all you need is a better corporate travel portal, which is a legitimate workplace productivity discussion to have, and a solved problem with traditional methods. Ours is effectively close to the workflow you describe: picking dates and time brackets, destination, fine tuning flights and hotel options, sending for validation, less than 10 clicks through information-dense and effective/predictable screens which I wouldn't want to trade for a chatbot and it's usually over the top words salad.