Weapon Finesse at first level wouldn't make a rogue as good a melee combatant as a fighter. Let's say a strong (18 str) fighter and a dextrous (18 dex) rogue walk into the same fight. The strong fighter adds 4 from strength and 1 from BAB. The Dextrous rogue without weapon finesse adds whatever low str he has (let's arbitrarily say 13, so +1) to a 0 BAB. The fighter is ahead by 4. Now let's add weapon finesse to the rogue. The fighter is still swinging a 5, but the optimized rogue is swinging a 4 (18 dex + 0 BAB), not exactly what I would call an equal combatant, especially since there aren't any dex to damage feats and he is most likely swinging a short sword. Let's give the rogue the best possible outcome and say he successfully sneak attacks (but does not crit). He'll be doing greatsword damage, but still only have a +1 to damage from strength, compared to the fighter who could be using an actual greatsword for greatsword damage, wielded two-handed for strength and a half (6 in this case) damage. So the rogue with a feat he is not allowed to take will get a score 1 lower for the attack role and do 5 less damage, which at first level is at least one entire mook's worth of hp. And we didn't even let the fighter take his first two feats yet.
DJC