I certainly feel it is safe to say the general consensus towards alchemy cards is overall negative. Many arena players like myself simply want a convenient way to play magic online using decks we may already have in real life, or simply decks that we have created with cards we know of. Alchemy stands in the way of that.

Given that alchemy cards are generally powerful and their digital nature, players are left dissatisfied with the intrusion of alchemy cards into "paper" formats. Decks that do not utilize alchemy cards are very likely to fall victim to decks that usually do, with little or no resistance. Likewise, Alchemy cards do not belong in the Historic format, because they are not cards in magic's history. They aren't even cards.

Pioneer does not solve this because it invalidates decks that may be legal in historic, but not pioneer.

The way I see it, there's two ways to appease players who feel this way:
Remove Alchemy from Historic and similar formats, and potentially create Alchemy variants of these formats.
Leave these formats alone and create 'Paper' variants of these formats that do not allow alchemy cards.

TLDR: Many players like myself do not like interacting with alchemy cards and want to play formats that do not use them.