I typically don’t like to talk arts down.  I sincerely believe that every art has its benefits, and every art has its sportier or rococo technique.  When I started martial arts there was no one doing Brazilian Jiu-Jitsu, I did Kenpo based jiu-jitsu style called Ki Do Ryu.  It was, like so many styles, half Karate (kicks and punches and kata) and half self-defense moves based on material generally garnered from GIs having returned from WW2 with a few months of background studying with East Asian teachers.  In those days Karate often meant a grab-bag style.  Everything depended on what techniques your teacher favored.  No hard and fast definition of Karate or Jiu-jitsu exists.  And despite the modern codification of Judo into several levels of particular throwing techniques and a kata of ground moves, truthfully and classically, Judo was an anything goes fighting art indistinguishable from modern BJJ (incidentally look for BJJ to struggle to employ a similar codification and become another version of Judo in some realms).  Your instructor can and will teach techniques they are partial to, not necessarily just what someone like Donn F. Draeger (author of Asian Fighting Arts and other books on martial arts) says the art should be.  Even his old definition of the differences between the -do and -jitsu suffixes (do being “way” and jitsu being “war art”) was not universally accepted and arguments prevail.  Complicating matters is the fact that many practitioners of Judo in the old days never learned to say Judo and continued saying Jiu-jitsu despite the popular rational for changing the name.

Having said all that, I’m still very sold on the practicality of Brazilian Jiu-jitsu for these reasons.

1. Brazilian Jiu-jitsu has techniques for ground and standing, covering all possibilities of position, offense and defense, good and bad! It’s not hard to objectively look at a guard position and imagine you can pound your way out, and it even occasionally happens in mixed martial arts fights. However, there is still nothing better from that on-your-back, grounded position than using your guard (meaning engaging all your limbs so you can attack like a pissed-off cat). This isn’t religion, if there were better techniques (short of using weapons) we’d be training them.
2. Brazilian Jiu-jitsu like it’s alter ego Judo (as it is basically “classical” Judo) encourages free training. In other words, practitioners can spar with the material, wrestling for holds and positions, and thereby improving their fighting skills in a safe, controlled manner that is also a tremendous means of building stamina, and teaching calm in the storm. Karate and kickboxing have, of course, trained strike sparring forever, but grappling arts have often been trained as too dangerous to play with in free practice. The answer, and it’s one Jigoro Kano instituted 150 years ago, allows for limited contested struggle against partners to sharpen application skills. In other words applying holds on non-compliant partners.  Many arts, like Aikido, and most so-called traditional American Jiu-jitsu styles do not allow free practice with their techniques, and instead are trapped in a lock-step format of considering self-defense techniques as independent responses to particular grabs. This type of training is simply less effective as a self-defense fighting art.
3. Along with the practicality of improving skills and conditioning, free practice, what most of us BJJ practitioners call “rolling”, provides a wealth of other cognitive benefits. These range from simple enjoyment of game play (good in any sport) to the self-transcendent appreciation of the art as an independent creation summarily produced through the cooperation of the training (it is a kind of meditative state). The right partner can help you produce a kind of poetry-in-motion of human physical capability that is as beautiful as any ballet and as impressive as any feat of decathlon prowess. In short, the purity of fun in accomplishment in “rolling” is matched by few other exercises.

This is basically why anyone doing it for more than a year or two continues to do it. Prudence, sport and pleasure are the necessities of anything you want to train in and become good at.  If your practice has these items, you will produce naturally a tremendous self-defense without even having to talk about it.