Or a lazy susan. Whichever, you need a cabinet that turns the corner.

I am confused why the kitchen designer planned it like this!

It can be eliminated by not having another cabinet on the 90 degree angle ie: above the sink.

Angled reach-in. My favorite cabinet…holds a lot!

I have a lot of cabinets - I think that is why she left it dead....is that a stupid way to do the cabinets?

It's not a stupid way to do cabinets - it depends on priorities. Your designer may have been more concerned about symmetry on either side of the sink or about lining up the upper and lower cabinets. Since you have plenty of cabinets and are not concerned about storage, the designer may have focused on other things. That being said, it's your kitchen - if you want the corner utilized, let them know.

Have your designer plan for an easy reach cabinet

The corner cabinets are notorious for being difficult to store items effectively. Especially if you're short. I used to have an angled one that I hated because items would get lost in the very back due to cabinet depth. I now have a reach-in (like the first photo) and it‘s better since i can use bins to corral the packages, but it‘s still not great.

Personally, if I could spare the cabinet space, I’d leave it out.

I agree - if you don't need the space, I would leave it as is.

If you don’t need the extra cabinet space skip it. I am not a fan of angled cabinets and while it holds a lot I decided against it in my new kitchen. It’s a personal preference

I have used corners, blocked off corners and not put in any cabinets that would create a corner! None of the ways are stupid. It just depends on what your priorities are for the function and look of the kitchen.

The real question is why 2 sinks so close together? And it looks like you have head banging cabinets over the one sink?

Corner cabinets are a choice, if more space is needed. The cabinets over the second sink look awfully close to your head. Maybe you should eliminate those and add a corner cabinet.
I have a corner cabinet because I refaced what was already here.

I have what Carrie showed. I didn't know the name for it, so now I know I have a reach in cabinet. I find it extremely easy to use. I had an angled reach in (wynterwynd photo) one in our last house and the reach in is way more functional for me.

I design with "dead" corners often if there is ample cabinet space and if it helps with the symmetry of the cabinetry. An upper corner cabinet is 24"x24" minimum, so in your plan, it would have left you with a skinny cabinet next to the window. Especially when designing for a modern aesthetic, it's important that the sizes of the upper cabinet doors are consistent and balanced. It's one of those form/function trade offs.

Are the 2 sinks for kashrut? I wondered why you have 2 but looking at the layout I thought it might be for kosher kitchen. Otherwise usually one is a larger one and the other would be more like a bar sink.

We have a corner like that and the cabinet extends back into that space. It’s awesome. We store coffee beans and less used items in the area so it’s not dead it’s extended storage we can access.

@salonva yes it is for a kosher kitchen

I've had cabinets that used that space. It was just part of one of the cabinets that adjoined it. The inside of the cabinet extended into the space (called a "blind" cabinet maybe?). It was a dark space, hard to get into, and it ate things. But I sure was glad for every inch of storage and valued its dark recess.