A couple of thoughts:
First, beware of anything that starts with "as we all know. . . ." It may be true, it may not. But groupthink is groupthink -- even when it's Mustachian groupthink. ;-) College may or may not be insanely expensive, depending on how you approach it; but in the vast majority of cases, the value it provides is quite significant. For example, you may have been able to do your job just fine with a crash course in accounting -- but you'd never have gotten an accounting job in the first place without your degree. There is value in being able to get that first job, quickly and at decent pay.
Now, there are a lot of folks who would tell you that that reality is a bunch of corporate bullshit, and that we should judge people on what they can do and not on the letters after their name. And I agree! At the same time, I want my kids to be able to get jobs. And since I don't make the rules, well, for so long as the jobs require credentials, I'm going to put my kids in a position to get those credentials.
But I also think some of those complaints are short-sighted. Getting a college degree isn't just about the substance of what you learn; it is a demonstration that you have the intelligence to get into college in the first place (there's a reason people chase degrees from "name" schools), the work ethic to do the assignments, the executive function to manage all of your coursework and the logistics of managing your education, the attention to detail and mental flexibility to please a bunch of different professors, and the fundamental ability to learn new stuff that is reflected in your grades -- and, frequently, the self-discipline to manage all of these things while working a job, playing a sport, and/or pursuing a variety of other clubs and activities. All of these abilities are characteristics that companies value. Do you need a college degree to have all of those characteristics? Oh hell no. But the degree is a nice short-hand way for an employer to cut down the pool of applicants, without having to put in the effort to figure that out for themselves.
/Rant. Putting all that aside, all I can tell you is how I look at it: I see my job as putting my kids in a position to succeed in whatever they decide, within the realm of my own capabilities. Because I make a good salary, because college seems to be the most common path to success (it certainly was mine), and because my kids seem to be academically inclined and interested in the college path, I feel a moral obligation to use some of the benefits my own education gave me to give my kids the same opportunity I had. That doesn't mean that I will fund $300K for Harvard. But it does mean that I have put away enough to cover tuition, room, and board at a state school (in fact, I have done more than that, because both my income and my investments did better than I anticipated 18 years ago).
Your own approach will vary based on your own beliefs and means. $100K is quite significant (at least in current dollars -- who knows what it will be when your kids go to schoo?l?!). But rather than focus on a specific dollar amount, I would suggest you consider what your actual goal is, in words -- is it "pay for state school"? Or "pay for the best school they can get into? Or "be able to cover 2 years of community college and a transfer to a state school for the remaining two years"? Or "cover enough of college costs that my kid will be able to cover the rest with manageable loans and a part-time job"? That will give you a way to measure your progress over time against the ever-changing college costs to see if you are still on track to give your kids what you intend to.
The good news is that you don't have to figure all this out now -- you have many years to figure out what your kids are going to be like, what higher ed is going to be like, what jobs are going to require, etc. etc. etc. So just start putting money aside. And yeah, start with the 529. Sure, there are limits -- but that doesn't matter when you're just getting started, so might as well take advantage of the tax benefits while you're figuring everything out. FWIW, we had similar concerns, so we targeted the "state school" savings in the 529, and then saved extra money in our general VTSAX account, so it would be there if we found out we needed it, but would be accessible for us to use if we didn't. As of now, looks like we won't need it, so now it's a nice extra pot of savings for us!