Because it sucked.
2: Garbage collection is horrid.
3: Gpu, and cpu run independently.
1. Ashley only implemented a rudimentary 30fps mode. He has said that he firmly believes there is no benefit from running at lower than 60fps(though many PS3/360/One/Ps4 games and companies do otherwise). And more importatantly that actually running C2 at a proper 30fps would require a large foundational change to the engine. Which he doesn't believe that 30fps is worth while.
2. Not really any different than Java's. And Java games have well worked around that problem. So has Ashley.
3. That's kinda the point.
The prior request was to drop the render down 30fps. This one isn't about slowing the rendering. This discussion is about controlling the rate of logic. And from practical experimentation I found using Everytick 0.033 for logic would turn a 15fps to 60fps. Depending on the insensitivity of the logic itself. Of course overkill of gfx is still overkill on gfx.