I don't understand the hate for LED's in an EM. I can see not putting them in there if there are power issues that would cause them to strobe and flicker but as a way to get color into an old insert, plastic or backglass seems like a good idea.
Pins, especially of the EM era were designed to be cheap to manufacture so they just used regular white bulbs instead of colored but we have access to new cheap energy efficient bulbs. I would think if they were available as an option back when they were built, they would have used them.
Not every EM would look good with them, and placement and intensity needs to be considered but I don't see what the big deal is, it's not like it's a permanent modification that can't be undone.
To each their own I suppose.