Dream Theater isn't usually very lyric-orientated... which means the riffs, time signatures, themes and all are often build up and expanded on, before the empty lyric sheets are filled. That's another logical reason for working titles... it fills the void with no lyrical phrase being written.
Exactly. And just for fun, here's a list of the working song titles:
Death of Spock
Forever (original title)
The Battle of Jimmy Cocoa and Fishface
Creep with Tonality
Grab That Feel
Crumbling Metropolis
Oliver's Twist
The Keymaster
Beachhouse Reality
Squid
Puppies on Acid
Kittens on Crack
Blowfish
Fresca
Showdown
Carnival of Clams
Cat's Tail
Conflict at Ground Zero (actually a real title, changed after 9/11 before the album was released)
Move On (original title, changed for unknown reasons)
Jet Lag
Korma Chameleon
N.A.D.S.
Fisheye
Carpet Babies
Schindler's Lisp
The Pumpkin King
The Shaman's Trance (original song title, changed for unknown reasons)
Reap the Harvest
Bad Larry
Dolphin Safe
The Clover
Epic
Vinegar Seed
Smoothen
YARGGG
Easter Egg
(besides the creatively named songs 1-10 from the d/t album)