I mean for reference the sneak attack of the rogue only procs on the main weapon, which means a rogue is the one with the incentive to use two handed weapons.
There are two types of sneak attacks, backstab and actual sneak attacks. Backstabs are the ones you are talking about, i.e. only proc on the main weapon, are done from stealth and are indeed better with two-handed weapons. Sneak attacks, however, proc always when the conditions are met and can be done with two weapons. If you are going for a backstab build, having two weapon sets is advisable, but there are builds out there that make use only of a two-hander or sword and board. As for Paladins and dual-wielding, yes, they didn't manage to balance dual-wielding and two-handers, so dual-wielding is better DPS in 99% of cases. You use two-handers because they have special on-hit/crit effects, like Hours of St. Rumbalt.
Yep. And backstabs, requiring Stealth, are not very practical, outside of some niche builds and soloing or maybe sometimes as opening moves.
The vast majority of rogues will benefit more from dual-wielding. Nearly all of the rogue special moves are Full Attacks - use both weapons.
Yeah, Paladin signature moves are Full Attacks also. Particularly important for Kind Wayfarers, who heal 2x more with dual Full Attacks.
Classes more oriented on single weapon are classes with "Primary" moves - fighters, monks. Plus Barbarians - damage wise duals might be better, but because of Carnage aoe transmitting on hit/crit effects, two-handers rock for them due to generally superior and earlier weapon effects.