Fallout Shelter no longer seems to be dropping legendary items in the wasteland?

It is still possible to get legendary items, however, the chance is low. You wil most likely hit the 100 item limit before getting a legendary item. Looking at the game code for Android:

num = (timeForCertainSuccess * 60 * Random) / TimeExplored;
ItemRarity itemRarity = Normal;
if (num < 0.1)
  itemRarity = Legendary;
else if (num < 0.2)
  eitemRarity = EItemRarity.Rare;

The item chance is based on some modifier * 60 * random value, all divided by the total time the dweller has explored. If the chance value is less than 0.1, then the item will be legendary.

Well the game's wiki specifies that the longer your dweller explores the Wasteland, the greater the chance to find special and legendary items.

I haven't played the game before the patch (1.1) so I don't know how it was before and now it's a small chance, yeah, but not impossible... in the last 5-6 days I found 4 legendary items... I have a dweller exploring the Wasteland for 2 and half days, he found 2 items and 2 other dwellers exploring it for 1 day and a bit and they found 1 each. So it's not impossible but as I see it, it only happens when your dweller is out there for more than a full day.