I Guess....
....A lot of it has to do with how one likes to cook.  
I like a fair number of things that are spattery - meat loaves, roast chickens, ham, baked pork chops, etc.  And I vastly prefer open roasting to covered roasting.  So, self-cleaning is nice for those.  
But there is one thing above all others that makes self-cleaning desirable to me - turkey.  Now, I like a few slices of turkey breast as much as the next person, maybe more, but I hatehatehatehateHATE the smell of a turkey roasting, which hangs in the house until the oven is cleaned and the house is well aired.  
For banishing turkey odors alone, self-cleaning is worth it.  There has been many a Thanksgiving where I did without turkey rather than deal with that smell.  A poorly-maintained outhouse smells like Chanel No. 5 compared to the stench of a turkey roasting.