The 3D era characters are much less popular than the Trilogy era characters, with only a small handful of exceptions, the most popular of which have been included in the last few titles (Kenshi, Quan Chi). The four or five thousand people who want to see nearly half of the roster be 3D era characters is nothing compared to the millions of people who are planning on purchasing the game.
For the record I didn't even play the arcade versions of MK1-4 and even I wasn't that interested in Deception at the time lol. But yeah the Deception fans in particular are usually the most rabid advocates for this.
I've been playing since 1993 on arcades (I was 8 years old at the time). And I loved both the Trilogy era (minus MK3) and the 3D era with the rich lore