Why Fedora x86_64 only install 64bit library?

[yybs_sun]

By default, Fedora x86_64 only installs 64 bit libraries under /lib64 when OS installation! I think, it is not very good because there are so many 32 bit
application software, without 32bit library, 32bit application can not run at
all!!!

Why Fedora not install both libraries by default, any concern?

[Affix]

This is mainly because when you pick a 64bit system you are choosing to run 64bit applications and only require the 64bit libraries

you can install the 32bit libraries by adding .i686 to the end of the package name in yum.

e.g

yum install glibc.i686

will install the 32bit glibc libraries.

Another reason is to stop duplicate libraries taking up space on the disk(s) and your system hard disk

[oz]

Why Fedora not install both libraries by default, any concern?

Many users (including myself) would not be very happy if they had just installed 64-bit Linux and then found that the installer had installed 32-bit libraries on top of it by default. I personally don't need or want 32-bit libraries, so prefer those that do need them install 32-bit Linux, or add them if and when they should need them on their 64-bit Linux installs. Just my opinion, of course.