To address your first point: It's not really the dollar amount itself the owners would have an issue with, its the fact that all teams have 6 (or 7) cost controlled seasons of a prospect, with no competition or competition from others clubs, so offering someone a guaranteed salary that large would be completely unnecessary when, even if he is an all star hitter and worth a ton of money, you get the first 3 of those years at league minimum. By paying a kid that much up front, they'd be potentially changing the precedent for young player salaries, and starting to chip away at the one part of the game that is equal for all teams, those first 6-7 years of a players playing life. Once free agency hits, of course it's a free for all and while some owners may lament they fact they cannot pay 30 million per year to a player while others can, there's nothing they can do about it. Even the big spending teams don;t want to change what young guys earn, because that's how they can afford to sign multiple top tier free agents that other clubs can't. Take the cheap players away and even big market teams would see changes.
To address your second point: Pitchers have inherently more risk attached to them than hitters because all pitchers get hurt. Every single one. It's really only a matter of time. Position players still get hurt, but it's not to the same degree of pitchers. Every pitcher signed to a long term deal has more risk than hitters, no matter what age the pitcher is.