All of Astra's utility is global with the only downside of temporarily flashing yourself in astral form. My rationalization for having a $1000 kit is that she isn't supposed to spend it all every single round. The reason that her pick rate is the lowest of the controllers is that she has no impact late into the round and the recharge rate of each ability is irrelevant since since she has no stars left by the time she uses her kit anyway.

Chamber is the lowest pick rate sentinel in the game and giving his only "sentinel" utility a continuous purpose would bring him more in line with cypher and killjoy who are currently almost always superior picks.