Legendary cards on packs and chest should be guaranteed after meeting their chances similar like the airdrops cards are, as far as I know they currently aren't.
How it works: There is a 1.5% chance to get a legendary in a pack(using potions) each pack with 5 cards so on your 14 pack or previous packs you should get a legendary in case there you have the bad luck of not getting a legendary until them it should be guaranteed of getting them on the 14 pack.
Same with rewards cards after open the respective amount of chests and you has the bad luck of not getting one the next chest you open will be a legendary card.
Well why it will not be like this, what do you think of people opening 50 packs using 250 potions and not getting any legendary? they will not buy a pack again in their live, if there are a guarantee chance most players that buy a few packs will buy some more until they get their legendary at least or some players that wasn't planning to buy packs they get some packs in chests them they will want to buy some more to reach the guarantee legendary.
Is not very relevant when you open like 1000 or more packs but the majority of players just buy a few and there should be changes in favor of this majority we have a lot for whales lets give something to the average player as well.
This could go even further giving a guarantee Legendary Gold Foil after opening enough packs, it have a 0.064%(using both potions) so after opening 313 if you have not get a Golden Legendary you will get it on that pack, so people that buy a few hundred of packs will get motivated as well to get a few hundred more to claim their legendary gold foil.
And if there is any problem like increasing the amount of legendaries cards with this, it can be the opposite as well blocking the chance of getting a legendary in the next few packs after getting one.
This idea can help but by far the things that will help more to splinterlands is fixing the new players experience(most of new real players will leave the game after get a 90% lose rate against bots) and get new players, this two should have the highest priority but unfortunately seams their are in a low priority right now, I have ideas of this 2 as well:
Solution for Nightmare Bronze: https://www.splintertalk.io/@caimanx/easy-solve-to-the-biggest
Get plenty of new players without cost: https://www.splintertalk.io/@caimanx/idea-to-get-thousands-of
Here Another idea about rewarded owners of splinterlands assets : https://www.splintertalk.io/@caimanx/idea-not-trade-able-tokens