Alright well. Wolf's throw game actually has a lot of intricacies and is seriously beneficial on comboing particular characters. Something you need to be aware of to understand this is DI mixups, so just like DI'ing moves you can DI throws and particular DI's can help you get out of nasty throw setups; so what you do to counterplay this is use a throw which would put them in a bad situation if they DI'd for a specific throw. Let me show you an example.
So the good DI for B-throw is down and away, and the good DI for D-throw is in - this limits the opponents options when attempting to cover the throw, it also isn't the be all end all DI you can still mixup your opponent by doing a DI that they didn't expect. Also DI isn't black and white, you can get particular angles at particular percents which can be beneficial. So you see the benefit of mixing up which throw you're using to setup combos for specific throws.
Another thing to understand is positional stage advantage. I noticed this when you said "I also don't see putting an opponent above you with uthrow so you can combo with uairs useful either". Depending on the matchup, your opponent being in the air can lead to more than just a few U-airs. It also grants you immense stage control, Wolf's U-air is ridiculous at covering landing options; if you think about this, you can force them into an edgeguard situation, which is the ultimate goal in Smash. Also U-throw can also work as a DI throw mixup with B-throw on certain characters at certain percents into a double jump side-b.
I hope that helped you out to some degree. To really use a lot of this to your advantage you have to pay attention to what the opponent is doing and which him/her a lot during the game. Also if they're not doing anything about your B-throw chaingrab, just keep doing it; no need to mix it up if they keep doing the same thing. Tell me if you need to ask any questions