I don't know why there is this difference. The Spyro Reignited Trilogy has each game listed with "Reignited" added to the title:
Spyro the Dragon**: Reignited**
Spyro 2: Ripto's Rage!** - Reignited**
Spyro: Year of the Dragon** - Reignited**
This isn't the case for Crash Bandicoot: N. Sane Trilogy, wouldn't it make more sense to have them listed as:
Crash Bandicoot**: N. Sane Trilogy**
Crash Bandicoot 2: Cortex Strikes Back** - N. Sane Trilogy**
Crash Bandicoot: Warped** - N. Sane Trilogy**