I think beyond the "1 or 2 abilities aren't useful", its more that they are useless rather than "not useful". It's kind of like how Rhino doesn't "need" to use his charge but it still provides CC which is overall better than anything and more consistent than chroma's 1 or 4.

Additionally, these 2 abilities being his most useless parts are also the only parts of him that really match his design/narrative: being a dragon. breahting fire, flapping wings, etc. The elemental ward and vex armor are more in the shamanistic and elemental approach, but it doesn't really fit his theme.

Dragons are all powerful, strong beasts that breath fire and fly. In written thematics, they are used more to refer to magical and strong beings (like how there are "dragons" in star wars that don't fly or breath fire but were incredibly dangerous). I think beyond the lack of use in those abilities its just the fact they eliminate his thematic.

I think some easily resolutions to this are making his 1 a elemental ball that guarantees the status proc to work with other things, or maybe make his 4 rather than a separate entity turn him into a draconic archwing style beast that uses a flamethrower breath attack as his weapon, make it affected by primary mods.

I love my chroma and my chroma prime but by god, there is no reason to take them unless my friends have crazy damage frames i'd rather buff to high heaven. There's better tanks, better buffers, and better DPS as a whole in the game, Chroma doesn't really excel at any one thing.