I don't think it's a problem at all that you didn't enjoy it after A2. Some folks do (like Jorbs or your comment's parent) and some don't.
If your line of questioning was more along the lines of why it didn't wear off, I can give my own anecdote. I found that the increase of difficulty makes the game more interesting to think about because you have to be much more methodical in how you craft your deck and play it. There are a lot of variables to manage and account for too.