Honestly, my main complaint about this is that if you consider the types of people that would be willing to demand a contract amendment you can see that this kind of screws over junior employees and people who don't feel they have the social status to push back.

I've also had many contracts amended on request/insistence, but I have a lot of leverage. I shouldn't need a bunch of leverage to get obviously abusive clauses removed, a brand new graduate deserves to be subjected to it no more than I do.