Let's be honest, 99% of the things that you might accidentally leave at home, you can easily buy on the road.
I don't know what your plan is, but I wish I'd brought a water purifier on my first big road trip. I tend to seek out very remote places where potable water isn't easy to find, and having a little pump backpacking filter would have made my life much easier.
You don't buy motorcycles with your brain, you buy them with your heart. And who can explain love?