I love Steal... I use it religiously.
How does one forget that Edgar uses lances? (Tools are better, but meh).
It is the most efficient way of getting a complete set of Force Armors (assuming you care for it) and Genji Armors (well, after going through the Coliseum).
Then again... those that post there conceptualize that game way too much to forget how some of that stuff isn't so bad.... you could certainly live w/o the command, but for this moron here, there's a ton of awesome stuff to be had...
2nd Tempest (ebmid oh noes)
Drainer (way earlier than getting through the WOR Sabin scenario)
Economizer ('nuff said)
Ribbon (because "instant death" via zombie sucks balls)
Safety Bit (because "instant death" in general sucks balls, although one monster's attack ignores this item IIRC)
Force Armor (excluding the girls, you can have a set of this armor for all 4 guys)
Genji Gloves (because, you can only overpower yourself more)
Pretty much tons of stuff you couldn't get enough of, you can have tons more of...
Why hate on the ThiefKnife? :(
Replacing that over the Mithril Shield via the Genji Glove can easily be justified.