Indeed... When I got a couple of Gamma 6's, the engineer actually said "those are quite expensive when new" - which suprised me when you consider, as you say, they are prone to damage from vandals - and the optics aren't exactly modern now; a WRTL 2000 can provide better light distribution along a road. The china hat Gamma 6 I got was full of dead insects, and considering the work I had to do to get the canopy to fit and form a seal against particle ingress I think it had never been IP65 rated (despite the label) from the day it was built. Other lanterns like the Vectra have a cable gland in the spigot which can be tightened to for a seal and prevent the good old column spiders from making a home inside the lanterns - but the gamma 6 only has a fine piece of gauze... and this looks fine when the lantern is displayed, but as soon as you push a cable into the lantern this pushes the gauze out of the way and then the spiders can get in!Yeah the Gamma 6 is very poor by modern standards. I was amazed they were still in production until 2003! In the 70s and 80s they were insanely popular. As a kid I even had a 'Mr. Chimney-Pot' toy house which had a model version of one in the garden!
I've seen old drawings in kids books and cartoons which show what looks awfully like a china hat Gamma 6 on the street. The design is Iconic, and I think it's just that alone which is why it still gets produced, and installed.
There are still loads of them in Blackpool and all the roads they're on are all quite poorly-lit at night. The Gamma 6 is one of those old-school group B lanterns that lights the area around the column very brightly but then leaves a massive dark patch until you get to the next lantern. The WRTL 2000, as you say, is far superior and I've never yet seen one damaged by vandals despite some being in quite rough areas of town. Is the Gamma Basique really any improvement? I've never been under any at night. They look just like a Gamma 6 with a scarf wrapped around it's neck to me!
To be honest the Basique isn't really an improvement in optical terms, as the lamp is still vertical and unshielded. The bowl is still the same thickness and composition... if anything the canopy on a Basique is harder to put back on than it is on a 6.