Not many people are into FPV, for various reasons: complexity, cost, planes look more interesting from outside etc. FPV is but one rabbit hole among many one can explore in RC hobby. Allow me to share my motivations for diving in:
1. Double the utility for each plane - so I can fly both LOS and FPV. I don't have much storage space for many planes so adding the in-cockpit experience renews interest in a plane I am already familiar with flying LOS.
2. Experience the challenges pilots face flying the real deal on scale planes - for example, we read about the long cowling in front of Corsair cockpit blocking view to the carrier on straight-in approach. So fleet air arm pilots developed curved approach to land on carriers. Putting FPV camera at scale pilot eye position would allow one to experience the same challenges where a LOS RC flyer cannot.
3. Formation and dogfights - It's very exciting to see planes fly closely together as LOS flyers, but given the third person perspective, it's actually difficult to maintain safe separation at certain angles. FPV flying, especially with head-tracking, enables wingmen to maintain safe separation following formation training methods practiced by full scale pilots. Like this:
Same flight seen from ground perspective:
And when they get good at formation flying, it's also safe and fun to practice dogfights. Dogfights in LOS are very different from FPV. LOS pilots can always see if a bandit is behind his plane. Not so in FPV. When one is looking around and searching for bandit and trying to evade him in the cockpit, the adrenalin rush and panic feels very real. In short, formation flying and dogfight are a lot more fun and more realistic in FPV than LOS.
4. FPV is a much cheaper alternative to flying full scale - I am a rated private pilot. I used to rent Cessna 152's for training for $35/hr back in the 1990's. Now the rental rate at airports close to me is $250/hr. That's out of reach for me. Flying FPV replicates 80% of the enjoyment of flying full scale at a tiny fraction of the cost. And I can still apply most of what I learned flying full scale to fly RC planes.
5. Tap into endless resources on flight training for full scale pilots and apply same skills to RC flying. Case in point, check out this video for improving landings:
Or this video on formation flying:
Scale head tracking FPV flying basically bridge RC hobby to full scale flying and flight sim flying. It also excites people young and old to rediscover the joys of flying RC. The opportunities are endless!