I think it was a good decision. It is important (for new players and old ones) to keep the game healthy. Killing bots is a thing to do if you want to keep the game sustainable.

The sustainable game means you can invest your time (and money, if you want) in the game, and be rather confident that the game will survive and grow so your efforts won't turn useless. Everyone profits from this.

Another aspect is that I’ve noticed it's now better to aim for shadow rarity cards if you want to make decent profits

How do you know this? Do you mean you need to have as many shadows as possible or you are saying about having a full-shadow+ deck?