The point is, a completely non-biased game would be one that does not take advantage of any exclusive capabilities.
I would disagree with that. If I make the best 360 game possible, the best PS3 game possible, and the best PC game possible, how is that bias? I do all I can for all three systems, but I can't make the 360 or PS3 more powerful than they are.
You said it yourself, the three systems have different capabilities. The PC is more powerful than the PS3 which is more powerful than the 360, so it would stand to reason that games properly made for the PC and PS3 would take advantage of the extra juice the respective systems offer. However, by limiting all versions to the 360, they showed favoritism by only going as far as the 360 could and leaving the extra PC and PS3 power go to waste. That is an example of bias.
Just because a platform is capable of supporting a feature does not automatically mean that every game for that platform should have that feature.
No, but if a game would obviously benefit from such a feature, and it could be done, why wouldn't it? Like the UI. The PC has a couple features called a 'keyboard' and 'mouse', however the UI was designed for a console controller. All the systems got the same UI, which according to your argument would mean there's no bias. But on the PC, the UI is difficult to navigate because the keyboard and mouse need to act as controller emulators. How is it not bias for the console versions to have a UI that fits better with their input device, while the PC version has to have a UI that is horrible to use with its input device(s)?
Any decision to make some content exclusive, is a bias.
Only if it's arbitrary exclusion. If the consoles were capable of high-res textures and mods, you can bet they would have them. But as they don't have enough memory, and MS and Sony won't allow unchecked mods of this type, there's nothing Bethesda can do to fix it. They didn't make the consoles have limited memory, and they didn't make the consoles' user-content policies.
We bought the same game, did we not?
Actually, no. PC users bought a PC game, PS3 users bought a PS3 game, and 360 users bought a 360 game. The three are not the same, and treating them all like a 360 game would be bias.
Also, Bethesda didn't make the CK for modders. The CK is their own tool that they use internally to build the game (as was Morrowind's and Oblivion's Construction Sets for their respective games). What they did do is clean it up, remove certain pieces they weren't allowed to distribute, and release it publicly. Something to be grateful of, for sure, but they didn't build it for modders.