Igor is talking about some architectural changes that will most likely take place in the avast 5 release.
On the other hand, I somehow agree that the service could actually detect if ashDisp.exe has been killed and respawn it when needed... That would be quite easy to implement, actually.
BTW a similar thing is that when the SERVICE (ashServ.exe) part is not running, and you double-click the avast tray icon (which has the red cross on it), you get the dreaded "AAVM RPC" error message. The tray icon compoment doesn't even bother to have a look if the service is running, and if not, try to start it... This is another thing that will be addressed in v5.
Cheers
Vlk