I dunno about the whole 'multi-platform' thing. It can be good, if the games are made with time and focus spent on each of the individual platforms that it'll be on. But if it's a 'one size fits all' approach on the coding and game design... then they'll always suck on the more complex systems. Oni was a game where the PS2 and PC releases were at the same time, and the PC version had some attention paid to it... rather than the modern XBox360 era method, which is code for the console and do a half-arsed port of what could have been a stunning game to the PC.
I take it console sales are vast compared to PC sales and that's why we often get a port... It's a real shame as I often think PCs are slightly ahead of the game, though there are some things that are still not implemented in PC gaming that I think should be which is where I think consoles have excelled (such as services like x-box live - which has proved works well or even custom soundtracks).
The programmers do say that coding for both the Xbox 360 and PC are relatively similar, but like you say the one-size-fits-all route isn't going to make PC gamers sit up and go "wow" as often console graphics just don't translate well onto PCs (perhaps it's the sitting distance). BioShock case in point, I thought the texture resolution was pretty poor for a 'next-gen' PC game and when I looked outside of a window to see a low res background image wobbling in glorious under-the-sea-o-vision I just thought "bollocks, it's a port".
I wonder though would PC gamers be prepared to wait longer for an optimised game... I get a sense we're all pretty impatient and would probably be as annoyed with a publisher if they released a (simpler to program) console version before a PC one.