vicupstate, knee or waste, we're only talking about +/- 12 inches. If the planting is transparent enough, it will achieve your goal. I agree with the lack of sidewalk dining in Jax, there definately needs to be more. Having the outdoor dining elevated so that your eye to eye instead of eye to crotch with the street pedestrians in a nice touch, not to mention you're also getting a site line above the cars. The planting, depending on the height and level of transparency, gives the dining area a better feeling of intimacy, but allows one to not feel boxed in, if you can see over it when standing or have a view (although partially obscured) through. It also helps filter the car noise and street dust and debris. With this economy, I'm willing to not make to may critiques of any new development that show progress.
The rendering makes the planting look like a boxwood hedge, something to deliberately block the view. People watching is a side activity while dining, so why make it impossible? Someone that didn't know there was a restaurant there, could walk by it and STILL not know there is a restaurant there. But if they can see people seated there with plates of food, that won't happen. Not to mention, maybe the pedestrian will like what they see on someone's plate.
If I were building something that requires attracting patrons, I would WANT to get suggestions for improvements that would increase the chance for success. Making a change now is cheap and easy, it won't be once the work is completed.