It is all about how effective your serves are... and that obviously changes from opponent to opponent. Mixing up your service is key... if you can keep the returner off balance with a mixture of speed spin and placement it really doesn't matter what you hit for a first serve.
As a friend said to me last night... it doesn't matter how hard I hit my serve (my serve has been lacking pace since my return to tennis) I can back it up with a solid set of volleys (I do mix up my patterns well). It really doesn't matter how hard the returner hits it to me, it is more about where it is hit to me and with what kind of spin. Power up the middle of the court just makes it easier for me to make my volleys. Something taking me out wide and out of position is an issue as would be something dipping at my feet.
In the pro game I am not sure why it is not as affective as it once was... it could be that the server has less time to close the net... (faster serves and with the equipment what does come back shortens the time you can get in for a good first volley position). But at our level of play... you can make a good serve close on the net and have the opportunity at making a volley. It is still not that easy to hit winners off the return of serve on a consistant basis.
The other key to being a serve and volleyer is that you will be passed, it is part of the game and you need to be in the mindset to accept that. Like being a defensive back being beaten for a touchdown. Accept it and move on... better would be to learn from it and move on.