3 coaches associated with pitching may not be the worst idea. Pitchers are half the roster almost these days, so having only 2 coaches was always a bit light. I assume the Phillies are planning on having more than the 6 traditional coaches (bench, 1B, 3B, pitching, bullpen, hitting) from these moves with the additional coaches not being in uniform where there is a discrete limit.
There has been a creep towards adding more coaches: assistant hitting coach, catching coach, quality assurance coach - in recent years. The Dodgers have had all these positions at various times. The Phillies have had the second hitting coach position also in recent years.
It won't quite be the NFL where it seems every team has 20+ coaches these days, but the days of 6 major league coaches seems over even if some coaches like the 1B and 3B coaches will do double duty as fielding or baserunning coaches too.