1) Blue light interferes with their data
Telescopes need to operate in darkness. Blue light in particular is damaging to data collection. There is a reason that telescopes are often in remote locations. It’s because the darker the environment, the better their data.
2) Blue rich outdoor lighting is accelerating light pollution and rapidly blotting out the night sky
Many observatories are struggling with light pollution. Observatories located anywhere near a city was witnessing a disturbing deterioration of the night sky that is accelerating year after year. This is not just terrible for data collection. It is also a terrible tragedy for future generations. As it is, most people living in cities only see the night sky when vacationing. If the trend continues we will completely loose our connection with the cosmos and further disconnect us from the nature world. This is an important issue that we will be talking about in the future.
3) Blue light destroys night vision (even at low levels)
Moving around in a dark working environment safely requires your night vision to be on point. It takes at least 30 minutes to fully adjust to the darkness. People over the age of 70 need upwards of 40 minutes to adjust. All it takes to ruin that is a brief flash of blue rich white light. The bluer and brighter the light, the stronger the effect. The pupils immediately restrict to block out the offensive light and it will take another 30 minutes to readjust to seeing in a dark environment.