You are a 16 years old boy, which means you joined the forum when you were 12. Thats amazing. I work with a teen program here at the museum so I am going to answer this. As you can probably see, you are already correct in your first guess, which is that this is a tiresome subject for blasters, especially since the regular group here has run through the issues already on a number of threads...and thats why i tried to at least dig up a good one for you. But, no luck.
I actually did try to search for you because there have been a number of long and extremely helpful threads on this topic with much thought from many with a lot of information I am sure you'd find valuable in assessing these issues. I even looked at my own 'started threads' about a wood racquet era issue but I guess it was just a little further back than the memory allows on the site...it went only back to march 04.
Anyway, firstly, it is a bad idea to say things like "I cant imagine" that a chris evert could stay on court with a maria sharapova after saying you have "never seen her play". On what could you possibly base your imaginings?? (And as the old saying goes, "when you ass-u-me it makes an ass out of u and me") One reason it is complicated to compare eras is because the things that made you great in one era is often not fully applicable to another era, just as musicians who were great for what they did 30 years ago would be lost in a world of today that has different ideas about what music is, how it should be played, and even what its social purpose is.
In this, you sometimes have to look at the spirit of people to know their power across many fields of comparison, and there would be little doubt among any serious tennis historian, that especially given the wood racquets, that chris evert was monsterously more formidable than maria sharapova will likely ever be. she is a queen in every sense of the word, and sharapova at this time still a secretary in the Royal office, albeit a high ranking one who does more than order coffee. She's due for a promotion in coming years.
There is also little doubt the game was more complex back in the wood days...it is a harder tool to use, harder to be consistent with, harder to generate power with, smaller head to find the sweet spot--or even the ball on the strings--with. You had to use your head to win more, and there are still many many people, despite the trends, who believe that was a BETTER way to play the sport and what tennis brought out in people with those challenges actually enhanced better parts of the human spirit. But thats a whole other topic. But the point is there is NO WAY the players today are more intelligent on court. I would go so far as to give the fortune of every family I know as a cumulative bet that the players were smarter players then than now. Smart is not a word used for todays tennis. Demanding is a better word.
The players ARE more athletic today, yes. It is more of a business and the players more like CEOs than just athletes...whether thats good or not is another story...and they hit harder but in part because the ball was made to go faster through higher compression than even in the 80s and the racquets are more "advanced" at producing advantages for the players...again, is making it easier for a pro BETTER? or should they have to work for advancement through skill levels and not from racquets?? Just another question. Today's players are without question highly skilled, but greater tests would bring about the development of greater skill.
so maybe the question should nt be one of HITTING harder, but do the players WORK as hard? Physically, its more demanding today and they work much harder, all in all, on fitness and stamina. But mentally, they dont work nearly as hard. (If someone never falls riding their bike with training wheels on, its easy to say, "Look how they used to fall before! They never fall now!" But looks are deceiving for many reasons. And the media of any time is invested in the hype of the 'now'--that is what makes people buy tickets, not to mention racquet brands. But as always, dont believe the hype.)
Injuries have many causes, and some of it is the increase in hard court tournaments, the de-valuing of clay court events (the US Clay Courts used to be a major event, now gone, and the Family Circle cup was a giant for the ladies, but now is just another tour stop), but OVER-TRAINING (too much focus on physical) is definitely an issue. The truth is NO ONE knows why there have been so many injuries...it has never happened before. But I would bet that switching to wood racquets would eliminate them all, because my pet theory is that the constant strain of a ball hit harder than it should be cumulatively wears the body down. Hitting harder doesnt prove you're better, it just means you have the quicker instincts against being hit. I'd prefer a pace where the thinking player has time to think and not just react. I thnk that would make tennis a greater challenge as a sport and more honorable.
And lastly, Borg is a man with a wooden racquet who played very much like federer with similar dominance, but federer would also play as well as he does with wood. Wood helps touch & finesse players...its not as bad as you are thinking. I really would (wood) suggest you go and find a wood racquet that you feel comfortable with when you hold it. Then go find yourself a nice clay court. Then hit. You will find you have to watch the ball more, and may find that is a GOOD thing. And you will find more respect for the players who used that wood racquet to compete at the highest levels of the sport. For pure enjoyment, you might even find you prefer it.
By the way, it is relatively easy to find a copy of the 1980 Wimbledon final between Bjorn Borg and John McEnroe. (If you can find the 1980 masters match with them, all the better!) Check it out. I dont think you'll be complaining about the experience in comparison to what you see today. But I warn you, that eras tennis can be quite addictive!!