Well, the quality of certain releases is questionable to be polite. This does not help GG's rep. Unity suffered the same thing at one point. The engine itself is not bad, but that doesn't mean bad games are an impossibility, it depends on the dev using it. Unity for many is now a decent engine. Why? Because there have been a lot of quality Unity games released. Until Game Guru gets a similar mix of games out there it will be derided as useless.
A game like Minecraft is a bit of s different beast. The fact you can dig anywhere and alter the look of the landscape is a big factor. If you tried this in GG, with literally hundreds of thousands of objects (never mind polys) which are all dynamic, representing the world would literally stop GG flat. There's just no way the engine could cope in it's present form. You could make a very, very mini limited version or of course, something where you only farm objects around the map and don't have the ability to completely change the landscape. There are games out there like this, Minecraft is still reasonably unique in it's total control of the landscape and many only have control of the objects rather than every inch of terrain.
There's some good WIP's out there, which as expected may take some time to get released, but there's some good looking titles. Once a few are at large, things may start to look up a little for GG. Once we have a few more of the basics up to scratch, AI being the main one at present causing bad reviews (not surprising), I think GG may well get a better following. Oh, and more speed
SPECS: Q6600 CPU. Nvidia 660GTX. 8 Gig Memory. Win 7.