Exactly. I would add that, to me at least, humanism and Buddhism seem fundamentally incompatible, so in effect it would seem that one has to give way to the other. I suspect that what you are seeing as the loss of tradition is just the tip of the iceberg.
I think Humanism appeals to a lot of Buddhists, both in Asia and the west, simply because a lot of people simply don't really
believe in saṃsāra any longer. They might nominally say they believe in rebirth, but their planning, institutions and so forth don't seem to indicate a pressing concern for saṃsāra and the uncertainties it brings. On the other hand, charity work, social work and activism all tie in nicely with modern values based on the premise of perpetual progress, which is not only technological and scientific, but also moral (for instance, we have progressed in the sense of allowing women equal rights).
I've met Theravadin and Tibetan monks alike who want to justify their existence as monks by building schools and clinics. Saṃsāra doesn't seem to factor into their future planning. Progress is assumed as matter of fact, so in order to keep up with it they might as well further it along rather than standing by the wayside and becoming irrelevant and backward.
Asking people to support communities which are focused primarily on addressing saṃsāra is a tough sell to a lot of modern folks. With Tibetan Buddhism this is less so, but then they are the last form of Buddhism to "enter modernity", so to speak, so a greater appreciation for pre-modern values is to be expected.