Because they’re useless.
If a player went through the training portion, they’re ready to punish a Shinobi hard for even thinking of using them.
Which wouldn’t be so sad except that half his moveset and his only mix-up depends on him using them, not to mention the occasional “Well I wanted to do a normal heavy at close range but now I’ve fallen and can’t get up”.
Shinobi's ranged attacks such as the normal poke and GB are only used to counter attack, as is his purpose.
After an advance and flipping away, and the enemy throws an attack is when shinobi's ranged attack is meant to be used.
After an opponent whiffs (misses) a heavy its a guaranteed ranged GB and if he misses a light it's a guaranteed normal ranged.
His ranged attacks are purely meant to be counters and nothing else, as he himself is a counter attacker.
His light attacks, kicks and feints are the chain starters. The ranged attacks are just a link.