I can't say for sure why Riot decided to remove Crimson Akali, but it's not like them to remove content so i trust they have their reasons.
However, it's a poor move to simply replace it with a higher value skin that's completely different and act like it's fine. Good for people who like Infernal Akali or who base skins on their value, but others buy skins just for the look and don't care about the new recall animation and all.
If I wanted a flashy Akali skin, I wouldn't have Crimson Akali. And for those saying "get Blood Moon", there's no way I should be expected to buy another skin to replace it.
It's not about the skin "transforming" into something better, like the tree metaphor. It's having bought something and getting something else you didn't want, like if you had your order taken away and get another dish, more expensive, but that you don't like. It doesn't matter how much it costs, there's a reason it's not what you asked for.
Like that example or not, the fact remains that Riot is taking away something players bought for something some of us don't want. And i point out that we BOUGHT it, and as consumers it's normal to be expecting to get what we paid for. Riot cannot simply say 'we can't satisfy everyone." Also, unlike reworks and the like, skins don't affect the game itself and thus the whole playerbase, the issue is with owning players individually.
Now, having said all that, obviously people who prefer Crimson Akali can't just keep it since it'll be removed. But everything should be done to please up to the last person having the skin. They're simply flashing an epic skin to replace it, hoping everyone will go "Wow" and be done with it. Riot aren't the ones to cut corners usually, so how about thinking it through and come up with something that as many people as possible will like? Maybe make a skin that's more widely appealing? Or one not entirely different, since Crimson Akali is what people wanted? The skin was pretty much a recolor, so perhaps also make a chroma?
Anyway, I wanted to point out it's about more then whether you like the skin or not and I believe that we're entitled to something satisfactory for everyone. Riot did look for solutions in a similar situation about players not getting what they bought in the rune pages issue for Runes Reforged, and i hope they'll take things more seriously and do the same now.