I never got that as well. They could have beamed up either her or the guy she was trying to kill - vapourizing her was a bit extreme and unnecessary.

But at least it was a reason for Riker to have the Sads after having recently boinked her.

Maybe that's why he did it. Uta had regrets and was going to report Ryker for misconduct, so he decided to take matters into his own hands before his career was ruined.

I suspect #metoo is no longer a thing by then.

And besides, Troi would be able to read them both and find out the truth.

Pound Me Too is like a Genie set free that you can't get back in the bottle. Troi reading both of them to find out who's telling the truth doesn't always work. Remember the episode A Matter Of Perspective where Ryker was accused of just such a thing and Troi couldn't figure out who was telling the truth.

That's probably because the other actual participant in the case, the scientist/doctor/professor/whatever, was dead and not available to "read."

That and, Because Plot/Because Drama.