Why not ?

While I haven't looked at H.264 specifically many of the other MPEG pool patents have been
granted in Europe. 

Try getting the companies arguing against Theora to say that the encumbered formats are not
encumbered in Europe. Haha.

While software patents may not be directly enforceable in Europe, devices (including software)
implementing certain techniques can probably infringe.  Though this is outside of my scope of
expertise so I can't say much on that point. Whatever benefits the European system currently
has can not be guaranteed to last.

Beyond that, infringing US patents is unwise even if they can't be enforced in Europe... Since
a judgment against you in the US would be a problem if you ever need to do business in the US.
Perhaps this may not matter to a person, but single people aren't currently the subject of
patent litigation. Companies are, and this matters a lot.

This codec licensing stuff can largely be seen as a fight where there are a few LARGE and
deeply invested companies against a huge number of smaller companies.  The public suffers as a
result but they are just collateral damage.