A game like this simply isn't mainstream in the way say MW2 is. I think it would do a bit better at a slightly lower price, and having a PSN option probably wouldn't hurt, but I don't think it should be PSN only. I think they should have a bundle with a headset as well as Warhawk did.
In the end a title like this needs to find it's core audience to survive, and I don't think delivery mechanism would matter - although a price more in line with Warhawk launch might go down better.
It'll probably sell around 350 to 450 K week one going on pre-orders and after that it'll be down to word of mouth and finding an audience.
Price I think is the key thing for a title like MAG. At $60 dollars you're going to have to be sure about the title, so it'll only get the core audience. At $40 dollars you're going to get some people on the fence taking a risk.
I'm assuming they've decided it's better to get the core at full price vs more units at a lower price. I don't know if they have some view on likely price elasticity of the title driving this decision.
I'd like to see more use of different price bands myself, with $20, $30, $40 etc. titles to allow for more breadth of options. That would allow a developer to consider a smaller title with lower costs selling for say $30 vs a big expensive title at $60 with the price difference helping to ensure decent unit sales.
Of course we sort of have this, but it works in a negative way where titles that under-perform at $60 quickly tumble in price.
Try to be reasonable... its easier than you think...