Having skins that can be unlocked exclusively through hextech crafting is a good addition to the system, but the "price" of those skins should be reasonable.
Currently, Hextech Annie is "priced" 10 rare gems, which means its worth is 10 chests and keys, therefore 10 pieces of content that can be unlocked.
If you're lucky enough, those 10 pieces of content can be rerolled into 3 ultimate skins; if you're unlucky, they can become champions, summoner icons, ward skins, and low price champion skins.
If things stay as they are, probably only die hard Annie mains would go for the offer. Instead, if the skin "price" was lower (like 5 or 6 rare gems), more players would save their rare gems to unlock the exclusive hextech crafting content.
This is just my opinion and my point of view on the situation. I would really like to receive feedback from other players, so let me know what you think about Hextech Annie and if you think that the skin is worth its "price".