Nothing wrong following Thoreau's maxim to simplify one's life. Far from it, in fact. But how much simpler would your life really be if you just smoked navy flake and nothing else? You'd save some time on shopping and maybe some space and a little money from not having to cellar as much tobacco, but that would be about it. You'd still be smoking a pipe, still smoke roughly the same amount of times in the day, etc. Part of your reasoning to simplify your tastes is because you think it will make the pursuit of artisan pipes easier. I'm not sure how that would be so, but even if it were, artisan pipes are a very expensive and complicated hobby. I'm not seeing where the simplifying happens.
Also, a lot of these old-timers that pipe smokers venerate as being one-blend smokers are 1. not one-blend smokers, and 2. they lived in a time with far fewer options. The number of blends available now are immense, and any one of them can be shipped to your door within a week. That's pretty amazing, and I imagine if that were available to the people you mentioned, they'd be more inclined to branch out.
I think, if I may presume, you are attaching a certain romanticism to this whole one-blend style of pipe smoking. You see a utilitarianism to it that is charming in its simplicity. I can respect that, and if pipe smoking is a mostly just a means to an end for you, then yea, being a one-blend guy can make things a little simpler, much in the same way having the same breakfast every day can simplify your life (and I am the kind of person who does more or less eat the same thing for breakfast every day, so I get it). But whether or not this simplicity actually improves your life will depend on what you are actually try to seek out, from life generally and from pipe smoking particularly.