Great OP.
I still have to disagree on many points though. First of all though I'd like to comment on your examples from this months GI. Are all those reviews from a single issue? If so, I think a bias does becomes obvious in the pattern of their reviews. The fact that they keep falling back on the argument that largely relies on them bashing the wiimote is quite unprofessional from as third party gaming magazine.
Nonetheless, I don't think that only reviewers who prefer a particular control style should review specific games to their liking. We might as well then only allow racing fans to review MK, platforming fans to review SMG and stealth fans review MGS4...and the list goes on. Eventually we may as well only allow fans of certain series review those games, such as Mario fans reviewing the next Mario game. Instantly that system creates more bias then it posed to eliminate.
Reviews are meant to be an objective look at the game. Obviously much of what constitutes the score will be based on subjective measurements such as we've seen in a German magazine deducting points from MGS4 claiming that the storyline is too complex. Many fans would add scores for that very same reason. Either way we are left with reviews that in the end are little more than the opinions of the reviewer.
If you enjoy motion controls then I don't see the reason why reviews pointing out "flaws" regarding the control scheme of certain games should bother you, after all you know you will enjoy them anyway, possibly even more so than if those controls were differently employed. If you are a fan of both the Wii and Xbox or PS3, then perhaps such reviews may be confusing for you when deciding which version to pick up.
I saw a post here a few weeks ago or so suggesting that a way to make reviews more helpful and objective would be if reviewers tried focusing on different perspectives of the audience likely to play said game. I think by giving a breakdown on who would enjoy and who wouldn't enjoy certain games would be more effective than simply laying out your opinions about it. The point of a review afterall is to inform the general public, and so to make reviews more useful the one giving the rating should consider every demographic of his audiance and comment on specific features different readers may like or dislike.
Kudos to the person that made the suggestion. It is in fact something I will incorporate into my own reviews in the future.