This is true, but language, as much as fashion or culture, continually evolves. I don't know about you, but I don't run around town wearing a frock jacket and a tri-corn hat, nor do I wear knickers and spats (the height of fashion during BP's day). Just like fashion, the meaning of words can and do change over time, and we naturally shed words that have become obsolete or offensive.
There is nothing wrong with that at all. The BSA is over 100 years old, and in order for it to survive as an organization, it has had to continually reinvent itself for every new generation, and will continue to do so until it eventually becomes obsolete itself. Just like the Tri-corn hat and the spats, the Boy Scouts have changed their culture and fashion numerous times. I'm sure there was quite a lively discussion about the loss of manhood that followed the switch from knickers to shorts. "Shorts are for children, how can we expect our boys to grow into men if they're expected to wear shorts?"
The fact is, this may or may not be the time to shed the term Scoutmaster, and we can argue the merits one way or the other, but that's really not for *us* to decide if it's an appropriate time to change the term. The next generation and *their* parents are the real decision-makers, because if *they* make a decision, and the BSA doesn't listen, then, then they simply won't join, and the BSA will cease to exist.
As far as I'm concerned, if something as simple as changing a title increases enrollment and allows more youth to benefit from the program, then ditch it and don't look back. I can guarantee you that the children of today's scouts aren't going to be arguing about whether the program would have been better if they could have just referred to their leader as Scoutmaster.