As with nearly all capabilities in all fields, you're trading off flexibility, quality, throughput and speed to market. You're also trading off cost on the vectors of capex vs. opex.
Injection moulding gives high quality and throughput with low flexibility and relatively high capex. That makes it fit for use for some cases and not for others.
In my home 3d printer for instance, i can download and print a snowflake or some small toy my child wants to hang on the Christmas tree that she is missing in about 20 mins which otherwise would entail a trip to the store or ordering online and waiting. However, if i were to print all the decorations she wants to hang, it would take an inordinate amount of time and I'm better off making the trip to the store.
Injection moulding gives high quality and throughput with low flexibility and relatively high capex. That makes it fit for use for some cases and not for others.
In my home 3d printer for instance, i can download and print a snowflake or some small toy my child wants to hang on the Christmas tree that she is missing in about 20 mins which otherwise would entail a trip to the store or ordering online and waiting. However, if i were to print all the decorations she wants to hang, it would take an inordinate amount of time and I'm better off making the trip to the store.