What I tell people is to wet your finger and try to run it down smooth glass. Then do the same thing to textured shower glass or similar. You can easily feel the suction on smooth glass versus textured glass, ie 'structured' glass.
It is true that you benefit more when moisture and humidity are present and freeing the structure is extra important. I've found (whether psychologically or not) that even in cold and dry conditions the glide is better and beieve everyone would benefit to some degree.
As a performance minded, DIYer, I've messed around with various low tech, quick and easy, methods of structuring bases by hand and found that I can achieve excellent glide with rilling bars, sanding, wire brushing and other methods to impart grooves in the bases of my skis to achieve the basic goal of minimizing suction. With minimal imperfections in the base (and most will never feel) compared to a perfectly flat, machined base I doubt that if there is any REAL performance difference relative to glide performance.
YMMV and others believe a machined grind is the only way to go.....but the only way to find out what works for you is to try various options over time. There are many methods to achieve the basic structuring goals and for most of us, split hairs will not make a substantial performance difference. I find it interesting that people will ski Mach I on very abrasive snows and treat their bases like they are made of glass when they do base work.
In any event you need to free the structure after waxing to benefit from the structuring.
There are several discussions in this forum and here is an image of using a rilling bar: