Today's pros don't have it easier. They play against a level field, just like the old woody guys did. Just like Suresh said, tech has leveled itself to optimal level (for this point in time). You would never be able to compare generations anyways - today's guys are much fitter and real pros. Before you had pre-open era, which is a greater spoiler then the avdent of new materials.
And again, if we started getting picky about gear, should the sprinters go back from tartan to clay, to no starting blocks, or maybe to no shoes so we can compare them to the original Greek Olympians?
Get the America's Cup crews out of those cheater flying catamarans, back to the wooden gaf-rigged schooners?
Or any of the examples I gave before?
You cn not really reverse the tech. Things get different over the course of time. Easier, better (maybe?), more efficient... You can compare the people (not only tennis players) only by the achievemnts in their own generation. All the rest is just specullation...