She isn't a snob, she's an addict. It doesn't matter how she gets her fix, even if she has to murder some transporter freak, she needs to get the good stuff.
On the other hand, making the top notch pilot - you know, the one she sprung from prison because he was so good at piloting - also the assistant in sickbay was a questionable decision. Surely there was someone whose job was vacuuming the carpet in the crew mess hall, or some other less critical job, who could help in sickbay during emergencies, and not your top pilot who could save everyone's lives with his piloting skills.
Sorry. This always bugs me. I agree with you about Tuvix, but Janeway made some pretty odd decisions that everyone ignores in favor of Tuvix.
Come say that to my face and I'll personally give you the Janeway treatment. I'm sure I can program the transporter to turn you directly into coffee. :p