Gear Lust and Wanting Does Not Improve Creativity
Be honest, we have all gone through it. We all want the latest gear or something that we believe will make our work better. The secret is to realize it does not matter and will not improve your creative results. That said, yes it is possible to out grow your tools, but only in very rare circumstances. I have yet to find anyone that needed a new camera to improve their work.
Imaging equipment today is so good that rarely will we be at a lose to get what we aim for. Yes there are times that you might need something for a particular job, but surely you factored that into the pricing and knew when you took the project that it was special. With the exception of low light noise, I have not seen anything that has vastly improved over the past few generations from any manufacturer, with perhaps the exception of focusing systems.
Camera sensors have more than enough data to cover the print sizes of most people, assuming that they are printed at all. The point is, all of this has nothing to do with making you creative. It is you that sees an idea and works it until you get something that pleases you or the client. Have you ever heard a client say "I want 20 megapixel images, I don't care what they look like"? Work with what you have, and maybe see an upgrade as a reward for a job well done rather than an excuse to not create at all. I still look back at images I shot with a 110 film camera as a kid in awe that I was either lucky or smart enough to see the shot and take it without thinking about the hardware involved.
Think back to the early years of street photography for example, did Cartier-Bresson care about his camera or the grain of the film? Did Da Vinci care how new his pencils were? So please, always put creativity first and tools second.
I bet if you try hard enough you can overcome any problems to get the image you dreamed of, plus I bet your skills and techniques improve as well.