If they designed GLA with the idea that it would only be capable of being a Tank, then they shouldn't let you customize your GLA with skills outside of the GLA tree. What possible benefit could a GLA get from any skills outside of the GLA and MRD tree? ARC is pointless, LNC is pointless, PGL is pointless save 1 ability. So why not just lock all our skills to set specific standards? Why even let us customize if the point is "This is your Role, and if you try to do anything else you can't."

Sounds more to me like SE needs to make customization of classes more worthwhile. A GLA should be able to DD, and if they can't, it is because of flaws with the battle system and customization system. GLA isn't even the best Tank. So what is the purpose of a GLA if they're not even good for Tanking?