With its "Crimson Dive" attack, it can do 300 damage to the opponent's active Pokemon
Thanks to this, even after six unique reprints, not including Secret Lair, its remarkably expensive still
A second advantage of having a low creature count is that your deck is configured in a way to make great use of symmetric effects
find an easy test like a low shroud location or low fight enemy, attempt it and commit some combination of Watch This, Quick Thinking, Double or Nothing plus whatever cards you need to feel confident in over-succeeding, and then gain a bunch of extra actions and money and maybe a card if you had Pickpocketing or a Lucky Cigarette Case
Once a Lathliss player has established a sizable brood of dragons, they can activate her second ability to increase the power of all dragons they control
Better late than never