Of course it is. So is yours. Do you think this is a discussion, or a government fact finding mission?
First, for nearly all creators, pricing and size limitations aren't a problem at all. Trial can be 8 minutes or something else, it's up to the creators. The timed trial is the default one so you can save yourself the work of doing a proper demo while allowing the customer some way to try the game.
Second, of course you can't have XDK achievements and leaderboards, you are not an XDK game. It's like complaining your super free PC game doesn't have Steam achievements, it's idiotic.
Third, no AO rating it's also logical, like not been allowed either to do a Halo game, or use the LucasArts logo. Given that MS is in the end the one liable if you do something very nasty, and that nothing assures them a nasty game won't pass peer-review because they don't control approval, they have to protect themselves somehow.
Even in your dreamy PC world, some limitations also exist. You can't use IPs you don't have the right to, you may be liable to law depending on what you release and where you release it (happens from time to time in Germany and Australia), some tools may force constraints into you (depending on their licenses), and so on.
But like most people agree that the PC gives you a lot of freedom, the same happens with XBLIG.
The freedom on a PC and the "freedom to do what MS has said is allowed" on the Xbox are not even remotely comparable. It's a joke to try and compare them. On the PC I can put out anything that's legal where I live. On the Xbox, I can put out anything that Microsoft says I can.
If you can't tell the difference between those two things, then there really isn't anything else to discuss.