You also get the ability modifier to the off-hand damage without Two Weapon Fighting style.
A level 3 Rogue Thief with 3 attacks is a ridiculous damage dealer. I mean.. two weapon fighting needed some love but this is bonkers.
Stealth range is even more broken: Zhentarim hideout, half of Goblin camp, dark grove are all more or less soloable with one rogue and time.