As a world long drive champion and a professional club-fitter, I must often play a balancing act between the 'power versus good swing' theory.
Without a doubt, a repeatable and sound swing is the most valuable part of the golf move, and strength is always important, but I believe amazing things happen when the body is balanced in strength.
Don't confuse 'balance in strength' with having a balanced swing. What I mean is that the upper body is as strong as the lower body. Most of us are stronger in one area more than the other, and this causes problems, regardless of how strong some one is.
Just mentioning the upper and lower body is too general. Picture every muscle group in your body as the 'soundboard' or 'mixer' (pertaining to music). As you're listening to the music, you adjust every knob until you have the sound that you want. Once every part is balanced, the sound becomes different, pure, stronger, etc.
The same is true with the body! Most golfers are out of balance. If a golfer focuses first on the muscle groups that need to be strengthened in order to become equal with the stronger muscle groups, he/she could become physically balanced. Thus, they will see a better swing and a huge leap of strength and speed.
I recently returned from the gym myself,and after some testing, I was shocked to see how much out of balance I really was. (Thinking back to my baseball days and now long drive, I'm sure that I never was at my full potential.)
In a nutshell, a good swing is a result of a number of muscle groups supporting each other equally through out the golf swing. If your back is weaker in relation to the rest of your body, then the rest of your body will attempt to compensate to perform the swing… but it won't be a good one.
For example, if your upper body is stronger than your legs, the upper body takes control of the swing and, you guessed it, you swing over the top, out of position, etc. Similarly, if a golfer has great strength — upper and lower body — but his abs are weaker in relation to the rest of his body, he will have to compensate his swing for that weakness. Again, the results are less than optimal.
This explains why some of the smaller, thinner players with a balance in overall muscle strength are longer than bigger, stronger players.
There are a few trainers out there that can test you and gauge your strong and weak points and how to equalize them for a balanced body. Here at my shop, Wesley, our PT can test you as well, so if you're in the neighborhood, stop in. You'll be glad you did.
I hope this gives you some insight or at lease something to ponder.