First and foremost: Loi 78 is nuts, won't survive court challenges if it comes to that, and is largely unneccessary when the bad stuff a minority of protesters are doing (smashing windows, starting fires, etc.) is already illegal and the cops can arrest people for doing that without any additional authority. However, that doesn't change the fact that the students' demands are unreasonable, driven mainly by self-interest, and worst of all, they're presented as a solution to problems that would potentially get worse if Charest gave into their demands.
The amount of debt incurred to get a bachelor's degree, even if you borrow every penny of it, is small compared to the returns it brings over the course of a person's career. This is currently true if you attend an in-province school anywhere in Canada, and even if tuition levels in Quebec rose to the same level as the rest of the country, it would still be true. Is it cause for concern that in the rest of the country, tuition growth has outpaced inflation? Absolutely, but it's still a smart investment as opposed to the states, where I'd argue that the costs have gotten high enough that a positive return isn't guaranteed. Not all degrees are created equal, of course, but over 80% of university grads earn more than the median income, and as the gap between opportunities for high school grads and university grads continues to widen, it's likely that 80% figure will continue to increase. (Source: http://www.theglobeandmail.com/news/national/education/universitynews/university-education-no-guarantee-of-earnings-success/article2179803/)
I think it's smart that the Quebec gov't has ensured that increases are only going to cover inflation since the freeze, with (I believe, correct me if I'm wrong) a commitment to tie any future increases to the inflation rate as well. Something we can learn from the rest of Canada and the States is that increasing the amount people can borrow to pay for school is one of the biggest drivers of tuition increases (much like the housing market, but that's another discussion).
Should students have their tuition covered in full by the province which will tax its workers higher to do so, with no guarantees from the students that they won't leave for provinces with lower tax rates as soon as they graduate? No. Human nature being what it is, that's a bad idea. Now, if free tuition were combined with an income-contingent repayment plan that meant you'd be bound to reimburse the province for your education, even if you left the province, there might be something there. But I haven't heard any such proposal from the students.
Would freezing tuition at current levels make university more accessible? It's doubtful. Consider that Quebec has the lowest tuition in the country by a wide margin - it would stand to reason that they'd also have the highest university participation rate in Canada, but they don't. Not only does Quebec lag Ontario, they lag the OECD average. (Source: http://www.crepuq.qc.ca/spip.php?article1021&lang=en) I'm going to go out on a limb and say that bursaries and provincial loan programs are going to be able to cover the increase when it goes through, and that those programs will be configured in such a way that anyway who wants to go and has the grades can do so. Will people who hoped to graduate debt-free have to borrow? Probably, but they'll probably get a return on that investment. Are there people who don't qualify for loans at this time due to family bullshit, and will that continue after the increase? Absolutely, but that's a reason to reform student loan standards, not to cap tuition. The goal shouldn't be to lend more money to the same group of students as it's been done in the rest of Canada and the US, but to lend the same amount of money (inflation-adjusted) to a larger number of students. That's how you improve accessibility - by removing the well documented barriers to borrowing the money needed for tuition and living expenses. But I haven't heard any such proposal from the students.
I hope you're still reading, because here's the kicker: spending more money on subsidies for university students (which happens every year the tuition freeze continues) leaves less to fund the social safety net, and that problem, far more than the price tag of a degree, is what keeps young people from pursuing a university education. By the time I was halfway through 10th grade, I could've predicted with about 90% accuracy who in my high school class would go to University, who would go to College, and who would pursue neither after graduation... mostly based on their socioeconomic status. And given demonstrable trends in the demographics of university students, my experience likely wasn't unique. (Source: http://www.statcan.gc.ca/pub/11f0019m/11f0019m2003210-eng.pdf) My point is this: if ensuring that every Quebec student has the ability and means to get a university degree is the goal, holding tuition to $2k a year instead of $4k a year for everybody will pay far smaller dividends than putting those funds towards programs that address child poverty rates and improve elementary/secondary education, because most of the people who don't go to university have that fate sealed for them long before the question of tuition even comes up. But I haven't heard any such proposal from the students.
To the extent that they're facing a significant rise in their annual expenses, I completely understand why the students feel compelled to march in the streets. Hell, if the government capitulated after 20 hours of marching, that's a very nice hourly return on your time spent. But if you're wondering why people disagree with your protests, it's because you're asking current taxpayers to pay your way without any commitment on your part to pay them back. You're claiming that these changes will make education inaccessible when it's questionable that that's the case: keeping loan difficulties equal, increased bursaries will help those with legitimate financial barriers more than before. And you're suggesting that the best thing government can do to make education accessible is to keep tuition low at the expense of other solutions that address the socioeconomic reasons why 70% of Quebecois youth aren't going to University.