It would just be something else, possibly, to cause conflicts on web sites, browsers and maybe other software. Also remember a lot of web sites and forums dislike adblockers as it reduces revenue.
Unless there is an easy way to turn the adblocker on and off from the desktop then it is just more unnecessary bloat being added to AVAST.
I have the Adblocker+ addon for the two browsers I use already and it takes up no more space than a simple tool bar icon. Just click on that and you get all the adblocking options you should need. Even if AVAST included an adblocker and it worked as unobtrusively as that does it would be nothing more than a like for like replacement. In that case what would be the point of changing it?