A similar thought occurred to me last week. I am using an Olympus E-M10, and had been using my 4/3s DSLR lens, the 14-54 as my primary lens because it is so darned GOOD; and it IS good optically, one of the best lenses I have ever owned. I have a deep and abiding love for that lens.
However, the allure of that tiny, light kit lens, is pretty strong, IT is pretty darned convenient, especially as a walk around lens. And I am finding, that as I learn that lens and really start to use it to its best advantage, there really isn't a huge difference between the two. The difference is pretty much an incremental improvement.
The 14-54 is still better, and I use it for my planned shots; but none the less, I am getting some REALLY good photos from that cheap OLYMPUS M.14-42mm F3.5-5.6 II R. Maybe I'm just lucky, and I've gotten one of those mythical, one in a million accidentally great kit lenses, but I'm pretty happy with the lens, and I haven't had that sort of luck in the rest of my life, so what are the odds of it happening now? (Besides if I'm going to get THAT lucky, I'd rather win the state lottery )
I was planning to replace the kit lens with the 12-40 Pro, but I wonder if the kit really IS 'good enough'?