What are these awesome bonus actions that you are consistently losing your offhand attack to? [...]
Shove is useful in a few narrow cases when you find yourself on a ledge.
When people keep alluding to these bonus actions that other classes "need," what are they talking about?
It's not bonus actions that other classes "need," but bonus actions that all/some classes "have." E.g., Drinking potions, shove (many fights involve ledges), Hide, possibly special weapon attacks, and then class-specific abilities. These - including the benefits of increased MH/2H damage, the freed up Fighting Style and Feat/ASI, and/or the higher AC from using a shield - are often better options than speccing into dual wielding and using that BA for an off-hand attack.
However, one thing that I haven't seen mentioned (admittedly I've only skimmed this thread) is that in BG3, you can BA off-hand attack without making the MH attack (I think). This change by itself makes dual wielding more powerful than in 5e RAW.
And as others have said, the plethora of magic weapons also makes dual wielding more powerful than 5e RAW.
