That's because they replaced them with a pot that reduces every type of equipment durability consumption (you can get them from secret boxes). With this update they merged a lot of buffs together (camp base 2 buffs that got merged into 1 + 4 bought buffs that got merged into 1) so i guess that must be why...
Class Challenge Event, which happened in March 2015, had 3 tiers :
-Tier 1 was clearing White Tyrant's Challenge without getting hit(can't recall if it was hard or hero mode, i think it was hard mode to let everyone have a chance at it, and then lazy people just did that one). It awarded the "Class Challenge Event No1" title.
-Tier 2 i have no memory of, it might have been Weeping Queen (sort of a midway challenge for people who did not have enough gear but were eager to prove their skill) and awarded the "Class Challenge Event No2 title".
-Tier 3 was at first Titan Hero in 10 hits or less without pots, then when they realized it was too easy they changed it to Glas Hero in 10 hits or less, without pots, this tier awarded the "Challenge Accepted" title.
I don't have much memory of the other titles, but this one left a deep impression because of all the practice runs i had to do...
The saddest part of it all is that even if the monthly and weekly login gifts gave everything they could offer, it would still not be that great, just decent.
Of all the rewards only the runes and cadet badge (maaaaaybe mega is okay, but only for the spam memes) are "good" (and even that is debatable, as they only offer some more tries at RNG, runes for npcs and cadet for drops), rest is just pretty useless to anyone that is actually playing the game.
The fact that it's "FREE" also gives the player a sense of 'oh i can get it. i MUST GET IT.' And that is wrong because it's simply not worth the effort.
And THAT is the problem. It's bad because rates for good rewards will be nearing absolute zero, and will just serve to frustrate players even more ("Oh dang, i didn't get anything from the gifts in 12 months, guess i'll comfort myself by breaking a rune in one try"... oh wait)
At least with seal shop update they tried to make some decent non-RNG rewards, not too op because only for 90 weapons, but still good (assuming you reach +10 first ofc, but that's not the point). Those are the kind of rewards that are worth working for, not the ones weekly/monthly missions give out.