I hit the wall in Clicker Heroes. At some point playing the game you get to a spot where there just isn't anything relevant you can do to get better and I finally got there after buying 21 of the 28 ancients. I could farm up 40k souls very efficiently just one shotting monsters but the only useful thing left to do was slowly increase my current ancients in power - the remaining ancients were so pathetic in terms of return on investment that it felt sad to buy into them. (Thusia, Chronos, Khrysos, Pluto, Energon, Kleptos, Juggernaut) The last round of ancients I bought to increase my clicking at the end of a run didn't even feel worthwhile and these are much worse.
Unlike Cookie Clicker I can't just let the game farm up more stuff and slowly make progress. In order to accomplish anything of note I have to sit there and click on things regularly and when there are simply no more interesting decisions to make I can't see the use in sitting at the computer constantly pushing buttons to just make the numbers bigger. I do like numbers getting bigger, don't get me wrong, but Clicker Heroes has hit the absolute worst style. I can't click all the time but I have to be at the computer ready to click every minute or so. This means it is impossible to get into flow and yet it still keeps me from doing anything else. Yuck.
The game was fun and I liked doing the research to figure out the optimal line. I also enjoyed testing out new effects and seeing how buying various ancients changed the way the game played. Unfortunately unless new things are added in there just isn't any compelling reason to keep on Clicking. Cookie Clicker isn't really grabbing me either, but at least all I do is buy one more prism every day as I wait to get to 200 prisms - it doesn't stop me from doing all my other things.
I am very interested to see what sorts of idle games come out as time goes by. There is clearly a market for these things and I have a real interest in their evolution but I won't claim to have a good sense of how exactly they should be designed. It is still too soon and my understanding of how and why people play these games is not well developed.