Conventionally the switching node (LX) is of prime importance to monitor and verify the electrical and EMI performance of any power supply. Any bad board layout effect will be visible instantly by monitoring this pin. Our modules though have embedded inductors and internal compensation that reduces the BOM cost and simplifies the layout.However, a bad layout can still degrade a power supply by introducing unwanted noise and EMI issues. For example large ringing may occur at switching nodes if the PCB layout is not planned carefully. That is why the modules's datasheet has a separate section regarding the layout guidelines.If the device is not performing as it should the monitoring of the LX node gives us a lot of information that will help to troubleshoot the issue. Similarly, due to parasitic inductance and capacitance, the switching node (LX) may have high frequency (40MHz to 100MHz) ringing that could cause EMI issues. A simple RC snubber circuit can be placed there to dampen the high-frequency ringing.
Thus you can see that having the LX pin available can help not only in troubleshooting but can also help to alleviate EMI issues.