Well, I think there's value to learning about MO on a qualitative level, and the time investment and difficulty of doing so isn't huge.
Learning rigorous quantum chem is a huge undertaking. I'm working through three different textbooks on it right now, and I've got a few more on my list, and I still don't think I have more than a rudimentary functional comprehension of it.
Well, time is definitely a scarce resource. I'm not aware of anyone, short of a very few authentic geniuses, who did not struggle for literally years to understand quantum chem deeply. That's the experience of every grad student and professor I've spoken to, anyway.
Yeah. Most of the time, in practice, I'm totally pragmatic about it. Most of the time, I'll use VB theory because it's usually simpler and it usually allows for reasonably accurate predictions. If it fails, I'll try to consider things via qualitative MO theory.