So having worked at R&C the safety concern is exactly as poster above suggests. There are concerns about embers and therefore we were always told we had to lower them to reduce the fire risk. I'm not sure how much I ever believed this but this is what we were told and therefore had to do. I took the hit when we visited in May and sat in the umbrella seat as I like to refer to it.
There is an easy solution to that. If it’s a safety concern, remove the umbrellas entirely for this event so that people who pay so much money for a Illuminations package can actually see Illuminations.