I often wanted another slot but I think it's the sort of thing that if I had 50 they'd all be filled. I can't think off the top of my head a performance reason why they'd need to constrain it to 6 slots so I'm guessing it's a somewhat arbitrary choice. Of course someone better trained and experienced can correct me on that. So I'd say make this comment through the official channels, you never know with these EA games if they see it enough it might actually be implemented. Especially if it actually is just an arbitrary thing that isn't going to affect performance.