Attributed to an ENWorld forum person:
"Finally, let it be noted that sandbox play is not for the cautious. It only works properly for players who are risk-takers, and don't mind a higher death rate... For risk-averse players, or those too attached to PCs, sandbox games are inappropriate, because they induce a sort of paralysis, where, by avoiding risk too successfully, the PCs effectively remove themselves from the ranks of adventurers."
That's crap. Pretentious crap, even. Where I come from, we play games to play characters - having an attachment to the PC is the most funnest part. Casual PC death isn't exciting; it's a punishment. So my sandbox is less lethal than the one described above. I betcha my players will still enjoy it.
On another note, complaining about a secondhand quote from a stranger's years-old blog post isn't the most productive use of my time. Would anyone like a random chart?
COMPLICATIONS TO YOUR STANDARD FANTASY DAY AND ALL LIKE THAT:
1. Character gets a nasty cold.
2. Character sleeps poorly; is exhausted all next day.
3. Fierce rain or snowstorm.
4. Random person falsely accuses character of attacking/mugging them.
5. Pocket gets picked.
6. Witness a wagon accident.
7. Trip and fall; sprain something.
8. Town guard/soldiers hassle you.
9. Stranger hands character a sealed pouch/scroll case (1000 cp, map, mystery key...)
10. Two men pull a struggling woman into a coach.
11. Juggler or troubador won't leave party alone.
12. Charcter acquires a mysterious blue glow.
13. A main weapon is stolen... or is it just mislaid?
14. Plague victim sneezes on you.
15. See some wizard eye, which winks out immediately.
16. Loyal but protective dog attaches to a character.
17. Ornately-clad warrior challenges character to single combat.
18. Accidentally eat hallucinogenic mushroom.
19. Character mistaken for town hero - or local outlaw.
20. Messenger accidentally gives character someone else's letter.
21. Mischevious sprite swaps characters' belongings over and over and over...
22. Find wooden totem that speaks if touched (strange language?).
23. Cross a stream running in wrong direction.
24. Keep hearing thunder on a sunny day; maybe find recent lightning strikes?
25. Path has unexpected fork.
26. Townspeople refuse to talk to or do business with party (curse? guild threat? bad rep?)
27. All gold turns to copper (illusion, maybe).
28. Falcon dives at character when they try to eat.
29. Big monster nearby spooks horses.
30. A boot dies during travel.
31. Assassin tries to buy poison from you.
32. Runaway horse, or wagon, or something bigger - gryphon, wyvern...
33. Accidentally disarm a companion.
34. Locals demand surrender of all edged weapons.
35. Irritated wizard curses you to laugh whenever you lie.
36. Campfire gets out of hand.
37. Find a piece of apparently unattended jewelry.
38. Bard wants to join party (incompetent?).
39. Noble treats character(s) as servant(s).
40. "Oracle" proclaims an incomprehensible destiny.
41. Stumble upon fresh corpse.
42. Bottom of backpack gives way.
43. Someone is knocked into a mud puddle, or watering trough, or manure cart...
44. Receive word that a close friend is gravely ill.
45. Keep seeing the same scarecrow...
46. Fall into undiscovered cavern or barrow.
47. Lose voice somehow (or can only speak in rhyme).
48. Rations have gone moldy - now what?
49. Rockslide, falling tree, shifting sand...
50. Painful swollen spider bite.
...it's a chance to finally use that d50 of yours. I found this list in an old folder - I have no idea how old it is. I'd still use most of these.