There are a number of articles for and against expansion. Logic seems to be on the side of those holding to a 32 team final tournament (everyone gets a chance to participate and qualify already). Below are some excerpts from a reasonded article that I agree with.
As it stands every country has a chance to qualify for the world cup – that is what qualification is for after all. It is not the end of the world to not qualify for a World Cup. A line has to be drawn somewhere – it’s impossible to have everyone at the party. The current 32-team format works well. It is symmetrical, easy to understand, and has the right balance between getting the best teams in the world at the world’s biggest tournament in any sport, and making sure it is a World Cup and not just Europe plus Brazil and Argentina. You could argue Europe is over-represented. South America even more so – half of CONMEBOL’s 10 members can make it. In an ideal world, Europe and South American would give up some slots and spread the love to other parts of the globe. But everyone knows that won’t happen. So 32 slots is the best answer to a very difficult conundrum. It is certainly a big improvement on the previous format of 24 years last seen at USA 94 during which is was actually harder to get knocked out than qualify from the first round – a phenomenon which will return in a 48-team edition.
Proponents of an expanded World Cup talk about the current format as if the same teams win and qualify all the time. But that’s not quite true. Since the 32-team format came in, two new winners – Spain and France – have been added, an Asia side made it to the last four (South Korea), and every single year there has always been at least one team made it’s World Cup debut. This was not a format which was stagnant in any way.