I only have Analog Lab since version 2 and Pigments, and I'm not a keyboardist/pianist at all, but because I wasn't told about Logic's stock keys VSTs past Alchemy, I just used AL because I knew and could understand what those synths were supposed to emulate. I was given Komplete 10 in school, so I wanted to use those a lot as well. Even with the effects...when Logic released the Pultec, Neve and API clones, if you were new to Logic and didn't really know these at all, then you were golden. I do like them, especially the Pultec (Vintage Tube), and having worked with the outboard dealie, I'm pleased with its ease of use and sound. But are you, as a seasoned user of Logic and, let's say UA plugins, gonna stop using those and start using Logic's? And it's not even solely about processing speed for tracking or mixdown.
I imagine the ease of use and familiarity will be enough for some peeps to buy v8 or AL, but you have a point. It already exists in Logic in some way. They - and I, now that I know - just gotta get our hands dirty and get our ears ready for the shootout...