Stupid idea IMHO. PHP is great BECAUSE it organic growth. It fully exposes the incorporated libraries with the same naming convention of the library functions and often additionally also in ObjectOriented style.
Have a look how green field planned ObjectOriented Namespaces in Java and dotNet Framework 1-4 turned out. Java's String vs StringBuilder vs StringBuffer, Java's deprecated Date and Time classes, the whole "old" dotNet Framework has been deprecated for a slightly incompatible new dotNet Core namespace and several namespace parts got deprecated long before, some got useless with the move to asynchronous programming (something C/C++ based WinAPI supported since 1994), etc.
What history showed us that monolithic namespaces designed by committee doesn't work out that well, an organic growth may look ugly to you but is easier to remember and quite sympathetic - I for one like PHP also because of that. JavaScript, C99, C++11, have a similar long term history.
Also PHP is so great because of it best of class documentation on PHP.net - no other language has such an extensive docu (and for so many years) incl useful comments on every page. JavaDoc, MSDN, MozillaWiki, etc are unfortunately worse in every regard. (MDN is catching up; and even W3School is quite handy)