They will most likely never make hextech frags and boxes purchasable with IP because the implementation of this system was another way for them to profit through RP, while also adding a bonus incentive for all players.
You are not losing out by not getting items to drop: It hasn't costed you any money and you now have an extra chance to get some skins, champs, and wards for free that are already purchasable in the store with RP. The only thing that is available in the hextech system that you cannot currently get but straight up buying it, is the hextech Annie skin.
Psychologically, you may feel like you are missing out, but if you just ignore the key frags and boxes dropping and don't make them your objective, you will eventually get enough to unlock something and it will just be a nice free bonus for you.