Bordeaux, Burgundy, Champagne, Loire Valley and the Alsace region are all susceptible to cold winters, spring frost, summer hail, high humidity, rainfall at harvest and a host of insects and fungal diseases
And? You simply describe the realities of all who are involved in any and all forms of agriculture.
And there is a heck of a lot more to the "terroir" of a place that makes a great wine (or corn, or tomato, or wheat) than just the weather. A weather map alone means little.
however it could easily be argued that they produce some of the best wines in the world...the question is why. For one they have been at it for 1000 or more years than we have.
Wine has been growing where I live for almost 2,000 years. Age alone does not define greatness. And actually, nor does commonly perceived forms of "greatness" actually define greatness. The Western European wines are held as a "standard" but one could argue that is simply a matter of history, marketing, familiarity, or any number of factors that make these sources the "standard". Georgian Amber/Orange wines use a much older method. Maybe they should be the "standard" for wine from white wine grapes, not a French Chardonnay aged in oak barrels. What any one person or critic considers "fine wine" is often driven by these headwinds. But who is to say they are actually "correct"? They may simply be tradition. And maybe they are wrong.
Also many will say the best wines in the world do not come from optimum growing areas but rather originate in areas at the margin for growing that grape.
There is a saying: Wine grows where corn doesn't.
In other words, yes, one can grow wine in a deep loam soil, ideal for corn, but a vine will over vegetate. Yet to say the best wine comes from "margin" areas is a bit misleading. As above, the wine that people "decide" is great wine comes from providing that vine growing conditions that balance its needs and the wine maker's needs. For example, the wine maker wants a certain brix. And that requires certain environmental conditions to achieve. And that may be in a generically "marginal" area for corn, but it is, actually,
ideal for wine production; not margin at all. Such terms really only matter when based on perspective.
Many old world wine enthusiasts will say wines from California are fat and flabby with too much alcohol and are far too fruit forward and usually too much oak.
Meh. See above. Grow what is appropriate for the local terroir (and that may be a hybrid), and drink what you like.