Not when Plan A has well known well document problems.
> New developments based on new components, however Saturn V-like, are a risk.
Restarting production for RS-25 has risk. Using solids boosters for human space flight has risk.
The idea that magically the picked design has no are significantly less risk is questionable.
In terms of risk to human on the rockets the other designs out-performed the current design and they were cheaper.
> The only novel idea of Ares was putting people on top of an SRB, which was cheap,
I recommend you go back and check out how much Ares 1 cost. It was literally the opposite of cheap. It was a gigantic money pit for a non-commercially competitive rocket that was incredibly risky for human.
> but abandoned when they realised the vibrations would kill the crew.
Maybe the single worst rocket design ever. Despite the issues there were others metnioned.
However the whole Constellation program got canceled because it was horrifyingly badly executed and a bad plan in the first place.
> Back then, SpaceX was science fiction.
By the time SLS was designed they were not. And just because SpaceX doesn't exist, doesn't mean you couldn't do much better then Ares or SLS.
It makes sense for it to use the well known approach as Plan-A when the options don’t exist.
> NASA did a whole bunch of studies and these studies pretty much universally showed that the current SLS designs was flawed and a booster that looked like a modern Saturn V was the far better solution.
New developments based on new components, however Saturn V-like, are a risk. I have read a couple studies back then and, while I am not overly enthusiastic about the approach adopted, it offered minimal development risk.
The only novel idea of Ares was putting people on top of an SRB, which was cheap, but abandoned when they realised the vibrations would kill the crew.
Back then, SpaceX was science fiction.