"it just doesn't look right" - Years of brainwashing having used MS products?
I have to agree, I use OO more often than MSO at work and I have to admit that I always have the nagging feeling that something just doesn't look right, but I know it's me and what I am used to, years of using MSO, I expect things to look a certain way.
Sadly you're right though, the user's perception of a product is far more important than any other consideration, even if that product may be technically better or worse, cost more or less, makes no odds. When you buy car, you may find that you enjoy driving the £9,000 Peugeot as opposed to the £50k BMW, one just feels better than the other.
When my missus moved over from Windows to Mac, we bought MSO for Mac and she hated it, the buttons are not quite right, the formatting is not quite there. Ended up with 5 months of XP VM running MSO, before finally moving to use OO on Mac! Same company, same product and even after tweaking, almost same look, but MSO on Mac didn't feel right, even OO still doesn't "feel" quite right, but it's nearer to MSO on Windows! Luckily it was student edition of MSO/Mac for her college course, else I would have been severely out of pocket at full retail!