Sorry to be pedantic, but the problems were enumerated in the article. There are multiple major security problems with cookies, and their costs are in the billions of dollars per year.

Instead of "I don't really see the problem with X" I think you really meant "I think on the whole the benefits of X outweigh its downsides". Neither the article nor the OP has suggested getting rid of cookies. They're merely trying to broach the subject of re-examining the HTTP state mechanism to see if there are better ways to solve the problem.

To suggest that something is sub-optimal is not to necessarily suggest that its net effect is negative.