Nice one! I'm using firefox and the "input-group cb" div, the one with "Include Ladder Runewords" only looks okay at min-width: 992px. Seems like the element is floating on the "form-group well searchWell"'s padding @992px. That whole form box div thingy seems to behave weird over all when going between width's. I'm using the newest firefox.
Other than that it looks really useful!
Thanks for the report, just pushed a fix for it (just in time for the ladder reset too!).
But to answer your question, almost nobody has all of the runewords memorized, so when you get a two sockets staff going to that page and looking at the 1.10 and 1.11 page is quite difficult and cumbersome (ignoring 1.12 since those are all class specific). Instead you can just use a page like mine. Another use case: Say I have 20 different runes, what runewords can I make/almost make? You can use this to find out.
I've made a page that aggregates runewords and allows you to search over them. I realize there are already a few of these but I feel that they look dated and can be confusing to use (for first time users) so I made this.