Bummer to see Cooks go, but speed guys can be grabbed, and I'm excited to see Reynolds in a bigger role, I think he's earned it.
Nothing but respect and best wishes for Cooks, but this is a good deal for the Rams. Although Cooks is tough and capable, in retrospect his size was a disadvantage, as was his salary and the uncertainty of his health.
Reynolds has shown enough to step in and is a receiver with much more length. The Rams' passing game will have new opportunities with Reynolds and Higbee on the field together. Size matters.
Rams can also use the pick on WR if they want-- this is the year for that position. If not, they can now get both a top RB and Olineman in the second round- that would create a new look offense!--or one of those and a defensive player. Or they now have more draft day trade capital to go down or even (gasp!) up.
This is lastly another piece of what is now a comprehensive if not ruthless overhaul by the Rams for 2020, starting with the coaching staff. It appears that almost no one is untouchable if for any reason they do not or cannot perform. The Rams are not messing around.