I have accepted this recommendation due to the performance impact, and don't argue that. 

But I find that this has killed for me the utility of object-ownership in general.  Has anyone made good use of object ownership since following this "always owner-qualify object references" guideline?  I haven't.  Just an extra "dbo." that I have to add everywhere--more typing with no benefit.   

But back in the day, before this advice was proffered, we used to be able to use the ownership mechanism to implement some pretty cool workarounds.  Applications & procs had to reference objects with ".." instead of explicit owner name for this to work.  When/if we created non-dbo-owned objects, a subset of users would access these instead, getting whatever different behavior was desired.  I guess this could get out of hand if used recklessly, but when used carefully this was a great solution to some problems.  Can't use this anymore because all of our production code has "dbo."

Why, yes, I would like some cheese with that whine....