For me, LEGO(R) bricks are one of the greatest toys of all time. The possibility to make sturdy, great looking things from a pile of very basic, standard bricks, is unique. This worked back then, in the 1970ies and 1980ies, when I was a boy, as well as today - happily the LEGO(R) group released the CREATOR series. And even better, I like the plenty of details possible with nowadays parts, pushing people to be very creative and innovative. LDD and stud.io help also a lot with this, and is great fun, too.
This vast creativity and ingenuity of people out there is why I love to browse Rebrickable.
Unfortunately some digital MOCs lack of sturdiness... You can connect a whole sub-unit to a digital model by only one stud. While this works on the computer screen, it is clear that it often won't work with real bricks in front of you.
So, one of my goals is to help make things works.