If you assume that the pick would otherwise beat the odds of a late 1st panning out to a meaningful extent.
A lot of the rental for a 1st trades end up insignificant for both sides in the end. Sekera was the ultimate rental gone awry; the Kings traded for him and proceeded to miss the playoffs! The pick the Canes acquired was used on Julien Gauthier. The Kings only could have used it on Thompson or Kyrou or DeBrincat (the notable players in the 21-40 range that year).
Not really.
A future 1st round pick can be used towards a future rental,, and is generally required if you want to trade for a reasonably high-impact player with term. Every year, teams go into the "deadline period" with whatever draft capital they have to make additions.
Florida next year already has a cap crunch, and it's going to be extremely difficult for them to add given that they've got basically no picks to trade... and have also traded several of their recent higher picks (Heineman, Smilanic, Kolyachonok).
Selling teams also tend to like instant gratification with picks that they get to use immediately. If you're not able to offer "current year" picks, it generally means you have to pay with higher-quality picks.