Nothing personal and don't take this the wrong way it's a genuine question. Do you already have this different skill set or is it something you need to learn?
Half the battle is getting the information to be able to read the data you are looking at. I am quite confortable with writing hex code straight to memory the problem is getting hold of the manuals that tells you what bit of the code does what. The same is true of the millions of data bits flying around the data bus. If you have access the manuals I am sure you will have cake and biscuits coming your way from all corners of this forum. And your point about knowing your car will get you there, yes on most occasions modern cars will get you there, the problem is when they do break down you can't just get you tool box out of the boot and fix it like we could in the old days
My tool box used to be a small socket set and a bunch spanners and pliers.
Disco 1, I added a big hammer and a welder.
Disco 2, I added a dignostics
L322, I added a second diagnostics and recently an ocilloscope for when things get serious.