5. Practicing with an invisible partner is of little value
Anything and everything works on a cooperative partner. Thus if an application 'works' against a prearranged attack it gives no information on its combative value. The 'Aliveness' concept holds devastating implications for the TMA 'prearranged attack' training philosophy. If only practicing with a cooperative partner with prearranged attacks has dubious value, then practicing with none at all has much less. "But even boxers do shadow boxing" I hear you say. My response would be that you have not boxed and do not understand the purpose of shadow boxing.
This argument would have value if you assume the only thing the school does is kata.
Our school (kenjutsu) practices solo kata, and then has sets of kumitachi that take all movements from the kata and apply them in "real" situations.
The practice is teaching your body how to naturally move under certain circumstances and do it effectively. A boxer drills himself to react certain ways when a punch is thrown. Just as we drill ourselves to react in certain ways when a cut is made.
If you knew you were going to be attacked in the street in 2 weeks time would you practice kata between now and then?
If you had a ring fight (full contact or semi contact) coming up in 2 weeks would you practice kata between now and then?
If you were designing a combative/self-defense system, would you have kata in it?
yes, yes and yes.
Your arguments are also assuming that everyone here is training for combat effectiveness.
If what your looking for is good effective self defense then you need to get out of your dojo and goto this website: http://www.nononsenseselfdefense.com
(thanks to Aleksay for bringing this website up more than once.)