I think for me, I don't feel as invested in the setting as much as I would if it had been something I'd created myself. Plus, it feels a bit unstructured and lacking something, though I'm not sure what. I'm just not as excited about it as I want to be, and it feels like a bit of a chore trying to keep things moving, as opposed to feeling enthusiastic about things such as my writing and other stuff I do as hobbies. 

I was quite excited when I initially constructed the OOC, but now it's actually running, I feel a bit 'bleh' about it by comparison to other stuff I've done. I like the mecha, and I like that we have human characters alongside anthro ones, and that there's conventional (i.e. modern day) gear and equipment alongside the mecha. I also like the fact that there's some space-related content as well. But overall, I'm not so enthused by the general aspects of the setting so much. I don't know if it's because I'm 'playing with someone else's toys', or as you say, I haven't really constructed the plot as much. 
A bit of discussion and input would certainly help a lot, and I'd like to see what other people think. I have other ideas I'm floating about that I could always use instead, but I'll see what other people feel about the game as it is.