I think the original intent behind these skills checks was to provide special dialogue for people who highly invested in a stat. Before 2.0, however, the skill checks were so easy to meet that you could meet most checks in the game without having a specialized build. While it was probably great for people who like to use all of the special dialogue for a single character, it sort of defeated the purpose of having special dialogue.
So in 2.0 they added level-scaling to the special dialogue. Now you're not able to pick certain options unless you've highly invested in a stat. On some level, I agree with it. For example, I found it silly that I used to be able to reprogram the Delamain core with only 10 intelligence. From both a story perspective, as well as a developer perspective, only players with high intelligence should be able to do that.
With that said, I'm not arguing that level-scaling is perfect. However, when these special dialogue options were so easy to meet before 2.0, it really made them feel not special, and I feel that was not their original intent. I think it's important for people to realize that the special dialogue probably wasn't meant to be seen all on one character. Of course, with the free attribute respec they gave players in 2.0, there is still a way for players to see most of the dialogue.
In regards to the original poster's question, I imagine "reflex" is the Cyberpunk world's version of "perception", and it's often used when V perceives or detects something (e.g., in Wilson's case, they perceive his emotions), so only a V with enough reflex is able to detect Wilson's sadness.
I admit, it's sort of silly that you need a high enough reflex to notice someone is sad, but that's more of a design issue on why they chose this particular dialogue to be special, and not so much about level-scaling.