Why did they not at least just copy and paste the old Deep Gnome? RAW, they don't have Darkvision or Gnome Cunning anymore?

For these new humanoid stat blocks, I'd recommend taking a page from the 2014 MM and adding racial traits yourself.

Is this more work for individual DMs? Yes, sadly. But at least it's better than your deep gnomes being blind in the darkness of their own territory.

I'm confused, why are you talking about deep gnomes? This page just shows me the npc scout stat block.

@Hortitia, if you look under Appendix B: Monster Lists, there's a conversion table for 2014 monsters that have an 'equivalent' in 2025. Scout is the new Deep Gnome, Priest Acolyte is the new Drow, etc. I'm guessing WotC wanted 1) to claim that everything in the 2014 MM has an equivalent in the 2025 MM and 2) to keep racial stat blocks out of the 2025 MM. I guess this was the only way to do both?

Thank you for explaining. This solution doesn't seem sensible because I absolutely would have never guessed that this stat block is supposed to be a Deep Gnome. 

Guess it's simply homebrew to the rescue.

It's consolidation. Technically yes, Drow and Deep Gnomes were removed, with alternatives suggest to stand in for them. 
It's in no way implied that scouts are primarily deep gnomes, that's just one thing they CAN be used for.
Can we talk about how one of these guys still has almost equivalent DPR and longer range than a fully crewed ballista?
These guys and bandits are glass cannons, with high offensive ranged capability for their CR.
Not as potent as most melee units, but if they stealth, spread out, and kite from a distance, they're more dangerous than their CR would suggest.