Because we may as well pack up international sport and just play County/State/IPL cricket, where we can pick which ever nationality we want. Surely the whole original point of International sport is to pit one nation against another, not a group of people because it suits and can be financially afforded.
IPL was an example to show that yes someone from Pakistan can get work in India as a coach.
Players play the sport, coaches coach. From bottom up majority of your coaches are local (nation wise), in India almost all of the coaches below the national team are Indians but when it comes to a team that is going to represent your country on the world stage you want the best players, best staff & best coaches.
At least all our players are Indian since you bring up country vs country. You seem to stuck on english coaches, if you had a coach that was that good he would already have been snapped up by ECB, then either his career ruined or moved so he could be working for some other country.
Get the best
Wo/Man to do the job so he could take players from your country and make them winners, doesn't matter where that
Wo/Man comes from because its your country winning by getting more fans, people playing and getting interested in the sport.