I don't think trades are a relatively minor aspect, at least not in my experience. I'm always active on the trade market, and so are most of the guys I play against.
I think you've got to limit losing, because trading allows you to make short-term corrections, and removing that avenue only increases the importance of the draft and international free agency -- which provide primarily long-range benefits. I'm starting to think, however, that prospect payroll shouldn't be limited. That would go a long way toward curbing any excesses in the ML free agent market.
Also, the Rule 5 draft would likely take on added importance in this league.