Just finished readind Courting Danger- about Alice Marble (1930s). She was ranked #7 in the US and her coach took her to see Harwood "Beese" White, one of the first to study the mechanics and dynamics of the game.
He watched her play for a while and said, "That's the worst tennis game I have ever seen." Marble had believed that she needed to "grip hard and hit hard", Beese showed her how to get bigger results with less effort by using smoother,
unforced (relaxed) strokes- and she went on to become the world's #1.
I think it should be obvious that, seventy years later, it is still desirable to develop a style that takes advantage of physics and use the body and its various parts to create smooth, reliable, powerful, efficient strokes.
Now, somewhere, there was another post that suggesting that "All strokes are almost the same"- and this may be true for players that have worked hard to get the most out of their game and learn to use their body mechanics to best advantage.
But having said that, I can see on the local courts that there is a much wider variety of "styles of play" than you will find on the professional circuit. Different people struggle with different assets and weaknesses. Some will never be smooth or fast or coordinated, or have great timing, or access to coaching (and so on) and, these people may never achieve a "relaxed" efficient playing style. And, to this extent, I agree with the theme of this post- being relaxed is not everything when it comes to building ones game.
If you can get to the ball in pretty good position- that helps, if you can get the ball back over the net- another good thing, if you can place the ball where you are "aiming"- not bad, if you have stamina to outlast the opponent- good, if you have some variety and can react to different situations with required stroke- a plus. So, there are all these things (and more) that may help one overcome a chunky-clunky style. A smooth tension free stroke is good to have, but there are many other aspects to the game.