I've seen a lot of technically perfect photographs. Sharp, detailed, through and through. But far too many of them use these traits as a crutch, to make up for what they lack in impact.
Don't get me wrong, I like cool tech and sharp photographs, just as much as the next photographer. But if we relied a little less on lens sharpness charts, and a little more on emotion... we would see a lot more powerful photographs.
There is not a camera, or a lens, on this planet that can make you a better photographer.
I regularly make large prints. 24x36 and 32x48 inch prints are not uncommon. Earlier this year, we made a 4 foot by 12 foot panoramic print. Most of these large prints were made with a 5-year old Canon 5D Mk 2. And they look beautiful!
Yes, I am planning on upgrading to a new camera system this year. I understand that it will not make me a better photographer. Oddly enough, my experience has taught me that my photographs typically suffer (albeit initially, and only for a short time) after upgrading or changing cameras. I think this is due to the re-learning process. A new camera is an unfamiliar tool.
Remember, that is all it is. A tool. Great photographs are not created by great cameras (or lenses). They are created by being present in the moment, fully attuned to your subject.
Powerful photographs aren't created from using the 'sharpest apertures'. They are made from seeing clearer, feeling deeper, and by making stronger connections with our subjects. There is not a camera, or a lens, on this planet that can make you a better photographer. Use the tools you have, rather than obsessing over MTF charts or lusting over 'the next upgrade'.
Take pride in your emotions and your ability to connect.
Immersion > acutance.