On a contrarian note, and not necessarily one I agree with, Seven of Nine states in "Relativity"...
SEVEN: The Borg once travelled back in time to stop Zefram Cochrane from breaking the warp barrier. They succeeded, but that in turn led the Starship Enterprise to intervene. They assisted Cochrane with the flight the Borg was trying to prevent. Causal loop complete.
DUCANE: So, in a way, the Federation owes its existence to the Borg.
SEVEN: You're welcome.
So the actual point of FC was for the Borg to be there in order to cause Zefram Cochrane to finish his warp ship, thereby leading to the creation of the Federation, a unique source of plunderable technologies for the future...maybe only the Queen knew this...maybe subconsciously...