Many users like this function because it is very flexible and highly customized. Especially for a considerable number of desktop users, the use of "tiles" is not obvious, so reducing the occupation of "tiles" and "slimming" for the startup menu are the demands of these users.
Today, on Twitter, a user asked GabrielAul, the person in charge of Microsoft Windows 10 internal test, whether the start menu resizing function could be returned. This user needs this function very much, because he or she doesn't need so many "tiles" or such a big start menu. Paul's answer to him is simple: yes.
Although he didn't say when this function will return, users who like to customize the start menu can rest assured. We should see this improvement in the future preview of Win 10.