Gatka usually displayed is for demostration purposes. Therefore, you will find that the moves that are shown are the ones that are most "crowd pleasing". The real aim of Gatka which is used in an actual fighting capacity would be to strike and injury your enemy as quickly and effeicently as possible. A proficient gatka player will be able to do this instinctivly.
Gatka nowadays is mainly demostarated with weapons following Khalsa tradition. But a good Akhara will also train to fight without the use of weapons. The panthra (foot movement) is a very powerful tool that enables one to avoid being hit (very important) and to be in the right place to strike. Elbows, fists and knees become weapons, a good Akara will know how to use them.
Knowledge of were to strike an opponent to inflict maximum damage as quickly as possible (and thus enabling the fighter to move the next oppenent) would be taught. A figter cannot dwell on one opponent for long as he has to be ready for other enemies.
I agree with you that Gatka as seen on TV and demos would not be usuable on the streets but overall with complete and full knowledge Gatka is the supreme martial art.
I hope this helps answer your doubts.
Finally, I have been told that all other Chinese and Japenese martial arts (karata, kung Fu, Ju Jitsu etc) all have their origins traced back to Gatka.