There's been enough impact over the years from rentals to justify doing something. Ironically, it's been the 2nd round and below type that has produced the best results (Manson, Kempny, Hainsey, Gaborik, Guerin, B. Stuart).
The 1st round type has largely disappointed relative to the price paid; Kaberle and Savard were 3rd pairing defensemen and while Vermette scored a few big goals, he was also healthy scratched at times. Weight is the all-around good outcome to point to and that occured 18 years ago.
Not sure how to define Barbashev in those terms, who was traded for a recent 1st round prospect that has gone on to have a disappointing AHL rookie season.