The 32 bit libraries ought to be installed by default.
Why? Nowadays most everything is available in native 64-bit code. Those who need the rare exceptions can add the libraries.
I'll note that Slackware64 13.37 doesn't include 32-bit libraries and neither do most 64-bit Slackware derivatives (i/e/: SalixOS) for just that reason. I, for one, don't want a bloated iso filled with all sorts of stuff I don't need.
eMachines EL-1300G desktop, 1.6GHz AMD Athlon 2650e CPU, 4GB RAM, nVidia GeForce 6150 SE video
CentOS 6.5 (will try VL64-7.1 soon)
Toshiba Satellite A135-S4727, Intel Pentium T2080 / 1.73 GHz, 2GB RAM, Intel GMA 950
HP Mini 110 netbook, 1.6GHz Intel Atom CPU, 2GB RAM, Intel 950 video, VL 7.1