Well Honda has always prided themselves on their engineering, so with F1 moving to a spec series, I could certainly understand if they no longer wish to sink hundreds of millions a year into a faltering program that will just be a rolling advertisement (if anyone but regular fans will even notice that much).
Not to mention they're already doing great with a much smaller investment as the engine provider in a spec series - IndyCar - and I believe the IRL is opening up the engine competition which would appeal to Honda to show off their engineering.
And with Toyota finally winning in NASCAR, Honda might want to become the second Japanese manufacturer to enter there.
I still think the real way to make F1 competitive is to ban non-GP weekend track testing and test teams. Those along eat up nine figures worth of budget for the largest teams and the smaller one's inability to fund any testing outside of "official test days" means they are forever on the back foot.
I do understand why the FIA is so worried about costs in Formula One. I was a huge FIA Group C fan, but top-league Sports Car road racing has always lived and died from the manufacturers who campaigned in it, and eventually the price became so high that nobody could afford it or you get into situations like Le Mans the past decade or so where one manufacturer comes in, drops a billion on the program, and wins it all two or three times in a row to make their point and then pulls out, leaving a huge void.
So by trying to make it cheaper for the manufacturers to stay in, they are hoping to keep them around longer - though Honda's latest withdrawl has likely thrown a spanner in that one. And, in a way, the current allowance of "customer engines" and "customer chassis" made F1 somewhat of a "spec series", anyway, in the lower levels.
Some things like traction control and ABS I can understand banning because the World Driving Championship should go to the best driver, not the best computer programmer or engineer. That's what the Constructor's Championship is for.
