Sassy/clever Obi-Wan is always good value, agreed. But in this instance I think it’s more of a gain to cut Loathsom.
I do definitely agree that every lightsaber fight cheapens lightsabers, but like the battle droid voices, they are unfortunately just part of the fabric of Clone Wars. My hope is that even after my edit, TCW and Rebels remain the least good Star Wars TV shows- I’m just trying to up the quality of TCW where it needs it most.
I’ll always try to judge the inclusion of lightsabers (or anything) on their pros and cons- in this case I think Ventress having tricked them is a cool intro for her and adds some threat to the episode beyond just “TANKS ARE COMING”. But I’ll also always stay open to community opinion.