Of course it is possible that there have always been lots of crashes in the first week, it's just that prior to near continuous televison coverage they weren't reported quite so avidly.
I think that is it. We never used to have so much live coverage of entire stages on TV. It is like 24 hour rolling news makes mountains out of molehills and will focus on relatively trivial things to fill the airtime.
It is clearly not great when riders have to abandon due to crashes, but Henri Desgranges himself always said the ideal Tour where only one rider finished.
It is part of racing, always has been, always will be. Even the most skilled bike riders will be caught out occasionally, but keeping out of trouble is an important part of being a complete rider.
The pave was a fascinating piece of tour stage design and led to some amazing racing. Those who benefited were those who had trained extensively on them through the spring. Beyond being a very competent bike handler, I believe nibbers spent considerable time training on the cobbles in March April.
Sharp corners are always going to be present towards the end of stages in towns/cities. Not much that can be done about that. Navigating them is again a skill. Sure the speeds in the run into the end are very high these days, but the riders know what is coming, and again, many of them will have trained on the run in during the preceding months.