You are not alone in your confusion.
This has been one of F5s weaker product releases, and follow up development.
BigIQ is still not a replacement for EM, and EM is too much of a vulnerability to be running in any serious Production environments. This has created a huge product gap.
With that said, F5 is a ADC company, not an ADC Management Tool company,.. It is not their core competency. I would advise you to seek companies that sole purpose id ADC Management tools.
Anyone recall F5 See-It? This is looking like a pattern. ;)
I have POC'd BigIQ twice in the last 3 years, and it is still coming up short, IMO.