Dan, here, is not a particularly exciting example. But in general:

1. I would not discourage people from contributing, even if they contribute sentences that fit a pattern. They will probably also contribute other things.

2. Writings names in different scripts is non-trivial and language-dependent. The famous mathematician Tikhonov, Tihonov, Tychnoff, etc., and the philosopher Plato or Platon.

3. Declension of names is non-trivial in some languages. For example, in Finnish, Tomi-Tomin-Tomilla, Johannes-Johanneksen-Johanneksella. As such, having different names adds actual linguistic content. This tends to be especially true of foreign names.

4. It is most natural to write sentences that use names of the culture in question.

5. If there would be default names, which culture would they be from? I would prefer Väinö and Aino, personally, as they are good and traditional names with ties to Finnish mythology.

6. Different names suggest different genders in different languages. Kari is male in Finland and female in Norway, for example, by default.

7. It takes a lot of effort to police patterns. One can use the same to add new sentences and to translate sentences instead. Furthermore, this would be something one would have to teach most contributors one-by-one. Adding such requirements for contributing is not a good idea.

So: Several such sentences are not needed. It would take work and be highly impolite to police them. Unifying names would, in general, lead to loss of linguistically relevant content.