If you have a lot of open windows, then the task list could run out of space. The grouping of the windows is a good feature to don't loose the overview.
This is what I mean with "grouping":

There is a good Applet called Icing Task Manager. Install steps:

1. Open Applets via System Settings
   
2. Go to Download and search and install Icing Task Manager
3. At tab Manage activate Icing Task Manager and open its settings
4. In tab Panel change Title display to "Title" (or "App"). Otherwise only the icon is displayed and you can't tell them apart from the panel launchers.
   
5. Now you have to remove the old Window list.
   1. Right click on the taskbar, chose "Panel edit mode"
   2. Right click on the old Window list and choose "remove Window list"
6. have fun