Avoid Negative Recruiting
Let's say Mike Norvell convinced those older guys to put in the time needed to recruit at a higher level. The problem is opposing teams would have all the ammunition needed to negatively recruit against those older guys.
FSU had overcome many of the narratives surrounding the staff after their first two years. Opposing coaches would tell recruits they wouldn't make the NFL if they went to FSU. They'd tell them those coaches wouldn't be there because of how poorly the first two years went.
They told them FSU wouldn't win the ACC again or compete for a playoff spot(that's where the snub last year did a real number).
The FSU staff overcome all of those narratives. FSU had 10 players drafted in April and on the ACC last season(and should have been a playoff team). The staff all got raises and extensions after last year.
Now that massive changes will continue to occur, opposing teams won't have that same ammunition. It'll depend on who else gets hired, but the only thing they could say is that FSU will be terrible again, and Mike Norvell might get fired after next year.
There's some truth to that, but Norvell has at least shown he can turn things around quickly. These new hires will have recruiting ties and new relationships that can help.