You could do both though: first four qualifiers off the European list, the next 3/4 of whatever off the world rankings, the rest wildcards.
Although the European Tour "link-up" with the PGA will kill the tour off quicker than Ryder Cup qualification anyway...
It's sad that the Ryder Cup qualification process is done in such a way that it tries to prop up the European Tour, is it not?
If it is truly an even to test the PGA Tour versus the European Tour, then the players representing Europe should all be members of the European Tour. In fact, you could go further and say non-European players could represent them if they play on the European Tour. Likewise for the US Team, any nationality on the PGA Tour could play.
If it is US versus Europe (country versus continent), then the qualification process could simply be set up to pick the best players in the world, regardless of Tour they play in. They simply need to be European to represent Europe.
Imagine the quality of golfer in the European Tour gets much worse in relation to PGS Tour. Maybe the current selection criteria could end up you having to have a handful of players on the squad you are much more inferior to the rest of the side. Or at least much less experienced at playing in the biggest events.
That all said, I really do not think Europe would have had done much better regardless of what players were in that team. So I wouldn't be rushing out to drastically change the qualification process on the back of this weekend's result. Not sure I like the idea of 12 picks though. Partly because the Captain may tend to pick his "mates" in some cases, and overlook a much higher ranked player. Also, when there is a qualification process, you can see the players that are driven to make the team, desperately looking to do well to earn their spot. In doing so, they can be playing their way into form at the last minute to just make it. And the captain can use this as an example to show how badly certain players want to be part of it, which can help him out in his few picks.