It’s a Scizor with 15a/10d/15hp 1897 CP worth to power up?

Bug moveset is better than steel. It's good against Mewtwo - and psychics in general which synergises with steel's resistance to psychic, and if/when Celebi is released it'll be one of the best counters to it.

10 vs 15 defence is not too big of a deal, Scizor has good defence already but lacks HP, even a 10 def and 10 stamina IV Scizor wouldn't be that much different from a perfect one in raids, Mewtwo's Confusion will most likely overkill you and if if it has Psycho Cut then the raid is incredibly easy that a Scizor surviving an extra attack due to higher IVs isn't going to make a significant difference.

Steel doesn't have any major use currently as the types it's super effective against aren't relevant or there are better counters - ice usually have water typing which results in steel doing neutral damage, or in the case of articuno, it has a double weakness to rock, and fire has the same advantage as steel to ice but a good fire pokemon is much easier to obtain than a double steel scizor.

fairies are non existent and the currently relevant rock types, rhydon and golem have 2 double weaknesses.

My Scizor has those same IVs, and it performs excellently. Maxed it out and never regretted it.

With those IVs, it has its last offensive breakpoint for Fury Cutter at level 31.5 and its last defensive breakpoint for Confusion at level 34.5.

With 15 defense IV, that Confusion breakpoint would also be 31.5, so if you are trying to hit the last breakpoint the difference is 6 power ups at 39K stardust and 42 candy.

But if you can manage to dodge Confusion without bugging out, the last dodge break point is already achieved at level 27.

If you are taking it 35 or higher then against Mewtwo the lackluster defense IV still affects damage from charge attacks but does not matter for Confusion.