Well no, I will casting this, because I want to make use of my bonus action, and it's one of the better uses of concentration for a first tier Cleric, and after I lose concentration on whatever you consider optimal I don't necessarily want to spend an action mid-to-late fight starting up a new concentration demanding buff, when I can use a bonus action to cast a spell with immediate and ongoing results. Clearly you won't cast it, which is a perfectly sensible approach as well, because it is now just an average quality spell balanced to it's arcane cousin Flaming Sphere, there are other things to do with concentration, and you clearly resent it's new status as an average spell of its level. But it's not some sort of trap option, it's just now ordinary rather than exceptional.
Okay, so...
1. Can you think of anything else that clerics frequently do in combat that requires a bonus action? I can think of a big one, and it's the reason my cleric often didn't get to make
spiritual weapon attacks even when it didn't require concentration.
2. If you think a 1d8+mod bonus action attack is one of the better uses of concentration for a first tier cleric, I don't really know what to say about that. It's not better than
bless, right? Like, even if you're alone, it probably
still isn't better than
bless in most scenarios, but presumably you won't be alone very often.
3. Yeah, it's balanced against
flaming sphere, except it has no area denial, doesn't deal any damage on a "miss," has a third less mobility, and can't set anything on fire. I mean, if
flaming sphere dealt damage only on a failed save and did nothing else, would you consider it a "solid" spell?
ETA: Also, what's the deal with the "resent" nonsense? I promise I don't "resent" any changes in the new rules, and certainly not a nerf to a 2nd-level cleric spell. It's not as if D&D will be ruined if
spiritual weapon is a bad spell.