Sri Lanka are a great reference point for a minnow that improved ten-fold and they didnt need 20 years to go from a shit team to one that can now occasionally cause an upset. Bangladesh, for instance, have been around for 20 years and even tomorrow, against a rubbish SA team, you don't expect them to be much of an issue. Since the 2007 WC, they've beaten 2 non associate team in each WC - England, who themselves may have been an associate ODI team. I don't see how they've improved since 2007. Ireland, following 2007, have gone on to beat England and West Indies, in 2011 and 2015. Is that an improvement? Has participating in the world cup made them stronger? I don't think so.
I love cricket and look forward to each WC. It'd be great if it could provide the same entertainment that the Football equivalent does. Unfortunately, there isnt enough quality. Already, we're seeing these pointless games - Afghan getting tossed away like some pub team even with all the quality we know they have. As I said earlier, the ICC should look at other avenues to improve the quality of cricket in these associate nations and then add them into the WC. Right now, its utterly pointless.