Sales will sell anything a customer wants. Ground, express, ltl, ocean... Perhaps capacity plays an issue in some parts, but there has never been anything to the "They are trying to move Express over to Ground", this is talks between a handful of Sale Reps and myself.
Ground is more popular because if the product allows it, $$$ matter. 2008 doubled down on that theory.
Sales Reps don't like nor drive drivers getting sales leads as you call them. I've followed up on this a while back, this is a directive above both parties, you are just following order made by others. No need for hate between sales and operations, those I work with are very complimentary of the job operations do. Are their exceptions, probably, but there isn't hate, nor is there any drive for them wanting you to do their job.