You do if you want to force them to develop faster.
"That which doe not kill me makes me stronger."
The main reason the Shivan were not as scary in FS2 as they were in FS is because we were stronger, more able to hold our own. Beam weapons:mad2: , Anti-Matter Torpedoes;7 , Meson Bombs

and all the rest of it developed out of the perceived need for better weapons to defend agains the Shivans. The Lucifer fleet served to strengthen the Terrans and Vasudans, allowing them to build ships and weapons almost equivalent to the Shivans.
The Shivans therefore destroyed a star to sheild us from the Great Enemy until our technology is equal to or superior to theirs.