A chap in New Zealand has decided that the best way to test his home-made pulsejet and turbine engines is to build a cruise missile test bed system. Sounds like a good reason to me!
A friend of mine, Ed, who was on the Heriot-Watt Fullbore rifle team when we won a competition at Blair Atholl range, built a pulsejet. He wore earplugs under his ear defenders, and the neighbours complained about the noise. His neighbours were, IIRC, 3/4 of a mile away, on the next farm! Sadly, I never got to see (or hear!) it run…
A valveless pulsejet with a reduced cross-section would be very useful for powering small missiles, as the design would have no moving parts, and would, therefore, be very much cheaper. A detonating pulsejet would also be very efficient compared to most pulsejet systems.
These are both areas wide open for the home-builder/inventor, since pulsejet design effectively stopped in the commercial sector 50 years ago! For this reason, great leaps forward are possible, as new ideas can be brought to bear, new materials can be exploited, and better tolerances can be used. Just remember the ear protection!