All year 1 legendary class items need to become infusable or you are going to annoy a lot of people.
My three faction cloaks and bonds which I've had since the beginning of Destiny, should be able to be relevant up until year 10 of Destiny...
Imagine the look on some of the players who started playing say, year 5...
"where did you get that new monarchy cloak?"
"I was one of the first in the Crucible, young guardian"
Or
"Shit, I have worn this vault of glass cloak since the start of raiding, I love how shiny it looks with my Queen's Web shader.... its a shame I'll never be able to use it while I play high level content now, I'll have less DPS, take more damage and have an impact on my raid or trials teams"
Honestly, bump if you agree, this is a bullshit decision and the only way to fix it is to make ALL year 1 LEGENDARY class items infusible in the infuse system, coming out TTK.