Dang, they aren't catching the booster this time, but I guess V3 is practically a new vehicle and validating the next Starship launch is probably too critical to risk damage to the launch site for now.
They're already highly confident that if they have sufficient control over the booster trajectory they can execute the chopstick catch, so they don't particularly need to demonstrate that part more. Executing a pseudo-landing at sea lets them validate their booster flight controls perfectly fine without risking the launch tower and associated hardware. They can also do stuff like stretch the trajectory and control mechanisms to their limits to see how much they can handle, and not too big a deal if something goes wrong. Presumably any actual landings will be well within the known safe limits on all parameters.
I bet this first booster also has a lot of minor weird things associated with shaking out the manufacturing process, and they don't entirely mind testing to destruction the first one to get rid of it permanently and use the ones coming from a more proven manufacturing process for important work.
Super Heavy: 200000 to 280000 kg
Falcon 9 first stage (without Falcon Heavy side boosters): 25600 kg
That and there's no way for it to stand without a catch tower.
I.e. if they cut a hole in the middle of a barge and it was burning at touchdown "against" the ocean
I imagine water doesn't have the kinetic problems that chunks of concrete do, but also that's a LOT of energy for even water, so maybe there'd be steam issues?
And they won't attempt a catch with the first V3 booster because it's not worth the risk. They can build a new booster every couple of months. It takes much longer to build the launch/catch tower, and they don't have any spare towers yet. A catastrophe during a booster/ship catch would set them back a year, so they'll only attempt a catch if they're confident it will succeed.