There should be a sandbox mode with everything unlocked, every type of molecule scattered around, and the only viruses are the ones you choose to add. That would be cool.
If there is ever a sequel for this, I have an idea: make it so that you can add elements you have discovered to the world to change it, and you can reset the world if you want to without resetting elements.
I reveiwed some of the older comments, and saw some more about this type of thing. I think it's just plain annoying to not be able to have as many sheel maxs, guns, and other things as I want. Parts with skills having a limit makes sense, because it's manualy done, but other parts really shouldn't have limits.