An introduction to my question is that ultimately op-amps drive something with their output stage (i.e., they source or sink current). I am looking specifically at the current sourcing scenario for the remainder of this question.
The current that an op-amp can provide is sometimes shown on the datasheet as its Output Current and even more rarely a Short-Circuit to Ground Current is also provided. Quite often these values are very low, perhaps single digit mA or maybe 10-20 mA, maximum. Manufacturers are quick to point out how little current their op-amp uses, but it's the driving ability of the op-amps that is paramount for many circuits. Without drive ability, one has to add additional gain stages that reduce the wonderful characteristics of the op-amp (e.g., noise, offset, etc...).
This current drive ability seems very small and I am wondering why the op-amps are designed to source so little current, forcing one to add another active stage after the op-amp for current amplification in order to drive larger loads.
To get higher currents, one has to venture into the world of so called power amplifiers, but often these have much worse characteristics on their datasheet than good op-amps. Also, they are much more expensive for decent ones (e.g., 10x as expensive).
Is the low drive ability of op-amps a side effect of trying to give them their good characteristics? Do these characteristics get worse if an op-amp is designed to source more than say 20 mA or so of current, that being the reason why they are so limited in their drive ability?
Update Perhaps an aspect of my question is why there is such a large gap between op-amps and power-amps (i.e., the jump from 10-20 mA to 2 A).