Nothing changed, it was never a good question. There are many ways to be productive, entrepreneurial, and creative while working "within the system", so the question was intrinsically discriminatory to those who did so.
And are most YC applicants significantly revolutionary? How many systemic barriers would you expect to hit if you have some insight on how to build the next popular photo sharing app, for example? And if they are applying for YC and answering that question, it's not a safe assumption to make that the founders would have hit up against those barriers yet. A lot of YC founders are barely out of college and just turning their idea into reality.
So it is possible to get extraordinary results through the application of discipline to boring, traditional approaches.
I've flown a kite once in my life, as part of a competition, that I won. My kite flew more than twice as high as the next highest kite. After the competition, people asked how I got my kite so high, and my answer was just that I brought more string than they did. Some might attribute that to dumb luck, but I have a history of winning silly little competitions like this by being prepared.
If you can't fill the application form, you're already out
I guess it makes sense, if you can hack (in the traditional meaning of the word) something outside of 'tech' this shows that you understand something about entrepreneurs sometimes having to play with the rules or thinking outside of the box (which does not mean doing something illegal)
So, PG and the rest of the crew probably looked at the limited supply of "Hits" that they had, and tried to identify, in their minds, what characteristics they associated with successful founders.
For whatever reason, the ability to overcome obstacles, sometimes "creatively", (aka "hacking the system") was one such characteristic.
They may also have had a few successful startups as well that worked "within the system", but I suspect those made up small percentage of their hits, and therefore would be much harder to predict.
From my limited exposure to very successful founders (Those who exit with an IPO or acquisition of > $1B), they are all mavericks willings to do almost anything to be successful. Many (most?) of them come very close to the line of what a reasonable person would consider generally acceptable , and they all have vast number of detractors, and quite often casualties and lawsuits on their path to success.
Think about the various legal issues associated with AirBNB - the AirBNB founders were funded, in no small measure, based on their unwillingness to let anything get in the way of success, and certainly weren't going to let some status quo/system which said what they were doing was wrong slow them down.
I'm sure it's possible to be a breakout hit, and create a $1B+ company while working within the system, but the large majority of times it's done (80%+), it's done by those who don't completely work within the system - ergo a demonstrated ability to work outside, increases your chance of falling into that 2-4% of very successful companies.