Well, the fourth striker to go along with Miccoli, Bojinov and Pazzini would mostly be for safety reasons, and the reason we're discussing it right now is because of the situation we're in right now (or were in just recently) with 2 of those guys out injured. We've had to start Fantini the past few matches because both Miccoli and Bojinov are injured. Now this 4th striker isn't someone that we'll be looking to spend a lot of money on, but is something we'll try to keep an eye out for to see if something can come our way. But you're right, right now the forward position is our lowest priority. Defence is probably priority one, with goal a very close second (or possibly goal first and defence second), and then wide midfielders third. I do have to say, despite our position in the standings, I don't think we're that far off with the players we have from being a very strong team.
Anyway, I think people on this thread that have said we need one more striker have also all said that our priorities are elsewhere, and in other threads where we're discussing how to improve the team you'll see people bringing up our needs in defence, goal and midfield, but this thread is a discussion of our attack, so that's why we're discussing a 4th striker.