I have probably arrived at this conversation way too late. I'm sure the boards are laid and well worn in by now.
To comment on the original question, Sure you can do anything you desire when it comes to building your own home. Sure, it may take a little longer or cost a bit more but the end result is ALWAYS well worth the effort. There is plenty of instruction on the internet with really good advice on laying your own T&G direct to joists. Anyone who tells you it can't or shouldn't be done is shooting down your ability to think and create alternatively.
I'm currently laying 70m2 of 150mm x 22mm jarrah floorboards directly to 50mm x 250mm jarrah joists spaced at 600mm. Luckily this is a mezzanine floor and the boards are at no time exposed to the external areas of the building. The floorboards and joists are visible from the underside.
If you don't like creaky floorboards, maybe give it a miss. Its a bit like rain on the tin roof. Love it or hate it.
If you go that little extra effort, people will visit your house and see something different. They will ask questions and you will be able to tell them all about your experience.