IMO, the main benefit of power steering (at least a good one) is to make the steering effort consistent between slow and quick driving. I've driven NSX's with and without power steering. I like the feel of the NSX with power steering because I don't have to adjust for the steering effort differences when the car is slow or fast (you can notice the difference on the track trying to make a slow turn vs going on a fast sweeper). Granted, the NSX probably has one of the best power steering system out there, which also points to the fact that steering feel is more than a function of whether there is or there isn't power steering.
That aside, I'm perfectly fine not having the power steering on the Elise, and I don't really see myself trying to parallel park the Elise on the hills of San Francisco. I'll be more concerned about break-ins and other cars touching it anyway.