A battle field is a complex, chaotic environment; that goes without saying. Contacts are both brief and savage yet the comments read as if everyone is standing around a sandbox shifting little plastic models around according to a computer generated scenario gaming 'what if's'. When the guy at the pointed end of the action requires support it is likely that he requires it about 20 seconds before he asked. Having to call and ask and then wait (even a minute) for an aircraft to be re-assigned to help out just isn't going to work. Further, assuming the closest aircraft suitably armed is heading for a high-value target i.e. a just-located command and control hdq. or field battery what chance does the chap on the ground have of securing immediate support? It will more likely be a "I'll be right back, don't go away" type of reply.
It is distinctly possible that a future opposition may be similarly armed and equipped as our own forces: witness Ukraine where both sides initially drew their equipment from the same manufacturer. Do you really want to rely on some stand-off weapons system at 10,000 feet to provide close-in support at 100 yards or would you prefer that the support visually acquire the target before commencing fire? If I recall, Tarnak farm involved an F-16 and a Lazar guided bomb from altitude further. Finally, it would be a brave commander, not looking for career advancement that would commit an F-35 into the range of hand-held ground to air munitions. It isn't going to happen.
We love to talk about smart munitions and how new systems are far more cost efficient but wars do not contribute to a balanced budget. Having multiple uses for a system may sound good in theory but as soon as you add a second purpose you simultaneously establish a priority order and I guarantee that CAS is not number one on any tasking list for any of F-16, F-18, F-35, F-22, B52 etc. etc.
Finally, and to get back to the topic, if you want CAS now, then you had better own it, otherwise, you are number 2.
