It wasn't designed to run on specific hardware, and originally ran on the IBM 709, which has registers. Lisp Machines were designed to run Lisp, not the other way around.
Why Lisp? For me, it gives me the freedom to get software written with the minimum of fuss in the least amount of time. I can keep my Lisp up and running, while I make changes to my code. I can type in and print out complex data structures without having to write parsers or print methods. I can experiment with data without defining new classes. If some functionality doesn't exist, I can add it: there's no distinction between the language itself and the libraries.
Maybe you should speak to more people who use Lisp, or try it yourself. If you don't know functional programming, you can still write basic Lisp until you learn it.
Why Lisp? For me, it gives me the freedom to get software written with the minimum of fuss in the least amount of time. I can keep my Lisp up and running, while I make changes to my code. I can type in and print out complex data structures without having to write parsers or print methods. I can experiment with data without defining new classes. If some functionality doesn't exist, I can add it: there's no distinction between the language itself and the libraries.
Maybe you should speak to more people who use Lisp, or try it yourself. If you don't know functional programming, you can still write basic Lisp until you learn it.