I absolutely would, if I were to make more wallpapers. When I made these, I had no such concerns, but I've grown since. However, I do not intend to go and edit the description of all my pony wallpapers because of this. Why? Because I don't think it matters. The guy has more followers than I have pageviews. I'm by no means a famous personality on DeviantArt, and I'm not producing any content anymore. If I were to change the descriptions to include credit to him, he would not even notice it in terms of pageviews, follows, etc. I absolutely appreciate his work, but I don't intend to do anything about this.
It's not really a matter of pageviews or followers. It's a matter that you didn't make the originals and there's no credit to the artist, which leads others to not know the original artist, such as here where you're credited with the original hearts.
Without credit to the original artist, you're really up for getting reported for art theft. I'm personally not going to do anything, but I am going to tell you that's a constant threat. It always matters. I'm certain if there was something you worked incredibly hard and originally on, you wouldn't want someone editing it and claiming it as there. It's something he gets every day and it's infuriating when you want to create more but have to constantly fear theft. I'm not going to do any more on this, and I'm not going to fight on it, but I strongly encourage it.