I dunno - they're individuals when you have fifteen of them, I don't know what would help when there's 150.

If you set off in some Terrifying location and keep getting the 'no migrants this season' message, then it really matters about individual preferences and keeping all your dwarves as happy as possible, as otherwise the rains of goblin blood and attacks from undead echidnas will reduce them to madness and collapse your fort. As soon as you turn the 'trade corner' (exported enough stuff that you get migrants again) then you usually see about fifty dwarves rock up over the next couple of seasons. That means:

• they take turns going outside, reducing individual unhappiness
• you can produce enough high-quality stuff to keep everyone happy
• the interface is less conducive to micromanagement - making sure everyone's bedroom is in their favourite stone when you've got to designate a hundred of them? When it's much easier to designate hallways of large rooms, masterfully engrave them, and fill them with identikit furniture?

The new interface is quite good in most ways compared to the ASCII version, but it still misses out on some of the features that Dwarf Therapist and the like have. If your migrants haven't brought you an armoursmith, then you might want to identify a fairly young dwarf with no other useful skills that has a preference for iron / steel, so you can train them up. That's quite a palaver to do directly at the moment - I usually choose a peasant at random - but it makes them less 'individual' too.