Why does PE 3.3.2 require gtk2?
GTK2 is currently required by the pe-java package. I think this is a recent requirement, since AWS linux images do not have access to GTK2 out-of-the-box and I was able to install PE 3.2 a couple months ago on an AWS linux image with out issue.
Not only is getting gtk2 installed on an AWS image a pain (you basically have to manually swipe the CentOS 6 package), but gtk2 also pulls in a HUGE list of dependencies... a couple of which must also be "borrowed" from CentOS 6 ((atk-1.30.0-1.el6.x8664, hicolor-icon-theme-0.11-1.1.el6.noarch, libXfixes-5.0-3.6.amzn1.x8664, libXdamage-1.1.3-4.7.amzn1.x8664, mesa-dri-filesystem-9.0-0.9.30.amzn1.x8664, libXcursor-1.1.13-6.20130524git8f677eaea.7.amzn1.x8664, gnutls-2.8.5-14.13.amzn1.x8664, libXcomposite-0.4.3-4.6.amzn1.x8664, libpciaccess-0.13.1-4.1.11.amzn1.x8664, libdrm-2.4.45-2.10.amzn1.x8664, compat-libtiff3-3.9.4-10.13.amzn1.x8664, libXft-2.3.1-2.7.amzn1.x8664, libgomp-4.8.2-16.2.99.amzn1.x8664, pixman-0.26.2-5.10.amzn1.x8664, libXxf86vm-1.1.2-2.7.amzn1.x8664, mesa-libGL-9.0-0.9.30.amzn1.x8664, mesa-dri1-drivers-7.11-8.6.amzn1.x8664, mesa-dri-drivers-9.0-0.9.30.amzn1.x8664, cairo-1.12.14-6.8.amzn1.x8664, libXrandr-1.4.0-1.6.amzn1.x8664, jasper-libs-1.900.1-15.5.amzn1.x8664, libthai-0.1.12-3.5.amzn1.x8664, pango-1.28.1-10.11.amzn1.x8664, jbigkit-libs-2.0-11.4.amzn1.x8664, libtiff-4.0.3-15.19.amzn1.x8664, libXinerama-1.1.2-2.7.amzn1.x8664, avahi-libs-0.6.25-12.15.amzn1.x8664, 1:cups-libs-1.4.2-52.19.amzn1.x8664, gtk2-2.20.1-4.el6.x8664)
So after getting all that in place and finally getting it working (usual installer fights aside), I naturally found myself wondering "Why the heck is this using gtk2, anyway??"
Naturally someone can just say "Use ubuntu" or whatever, but I think the larger question of why a collection of web services and a web interface need all of that X/GUI related junk is a valid one...