No? What the heck is everybody saying yes for? It's like they've never played adventurer mode. Just the other day I was playing an adventurer with proficient in their weapon and novice shield user and almost every time I got attacked it was automatically blocked with my weapon. If I was carrying two weapons it could double the blocking rate. Shields aren't necessary at all. They are necessary to block fire attacks though, and arrows are very difficult to block with a weapon, but even then it's possible. Wielding two weapons in Dwarf Fortress is a bit like using two weapons in real life. One of the weapons is mainly for defense, but you can still attack with it better than you can with a shield. Sometimes it can be a better defensive decision to not take a shield, if you put all your starting points into weapons, then you should be decent at blocking with that type of weapon, and if you hold two at once then you're even better, where as you'd need some skill to get better at using a shield. And I think blocking with a weapon will increase your weapon skill, which is more useful than raising your shield skill.
Though in my experience yes two handed weapons feel kind of pointless. It's just hard to tell when the exact mechanics of combat are so far away from our sights. Did the two-handed sword help me chop off their arm or was it random chance combined with their low skill and my high strength? You can never really be sure. It's not like you just can't use them though. If you want to use a two handed weapon then go ahead and do it. It should be fine.