this is true, when i had an accident i upgraded to depo replacements i got from scrapyard for about £15 each, and they are defiently much brighter and have a clear look to them.
the depo ones arn't brighter by design.. its just a much newer headlamp..
The original nissan ones seem to fade of the course of 8-12 years this is simply just the class as the front gets frosted with all the salt and debris striking it over the years...
I actually replaced Both my front headlamps for the same effect ( i.e brand new crystal looking ).. just DEPO ones are cheaper..