The G34/G35 guns are fairly popular for use in IDPA and other competitions, and due to this popularity, it's relatively easy to find holsters and accessories for them.
The longest longslides (G17L and G24/G24C) are either not allowed in certain competitions, or are limited to the highest classes, making them less popular with match shooters. Because of this, it can be more difficult to find holsters and accessories for them, which makes them (you guessed it), less popular (even with non-competitive shooters). It's another vicious circle...
"That means that no matter how we reform health care, we will keep this promise to the American people: If you like your doctor, you will be able to keep your doctor, period. If you like your health care plan, you'll be able to keep your health care plan, period. No one will take it away, no matter what." – President Obama, AMA speech, June 15, 2009.
see 13:20 - 13:58