Agreed.
Previous editions might have codified it, but this way, there is a lot more creative freedom in to how the DM can use it (or opt not to use it if it isn't appropriate for his game/group).
Like many things, contagious lycanthropy is now a plot development for DMs to use (or not use) rather than a codified mechanic.
If house ruling (put in spoiler block to avoid derailing this thread too much into house-rule territory)
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If you wanted to use it, all you might really need to do is use one of the given disease tracks (or something like LoustSoul suggested, above) and have the final stage be some sort of werebeast template. And then something in the form of a ritual requiring nature components to break it (or lessen it).
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