Yes, because they were replaced with better, more effective versions. You dont replace your PC componants with slower worse performing parts just because they are "new". You dont replace your 20-25 goal a season striker with a wheelchair bound toddler because hes "new". Warframe has the right ideas for guns, you know what happens when they release a new gun? Exactly that a new gun comes out and nothing more. If i want to tackle any new content with my Braton Prime (that i can mod to which ever -blam!-ing elemental damage i want when i want) i can. If i want to tackle it with the new guns? Well go right ahead. We dont need "better" guns, just lots more different ones. Ditch the -blam!-ing retarded attack values and leave our guns alone. If i want to spend the next ten years using one gun, then thats how i choose to "become legend".

Sounds like I [i]really[/i] need to start playing Warframe. O.o

Main difference with your example is that they were replaced by a better model that had better qualities. So far, Bungie has basically utterly failed in this regard with each new round of weapons that came out in the dlcs. They got progressively worse as the game went on compared to the vanilla guns.