Fingertip reinforcement isn't necessary for everyone, but it's a smart feature if you're hard on your gloves. The extra material layer at the fingertips protects against two common culprits: ski pole straps that constantly rub against your fingers, and boot buckles that catch and scrape when you're adjusting your boots in the cold. If you've ever worn through the fingertips of a glove mid-season, this feature directly addresses that problem.
Racers and high-mileage skiers benefit most from fingertip reinforcement since they're gripping poles tightly all day and fiddling with buckles between runs. It's also great if you ski frequently and want your gloves to last more than a season or two. The trade-off is a slight reduction in tactile feel—you may notice less sensitivity when handling small items like zippers or goggle straps.
For casual skiers who hit the slopes a handful of times a year, fingertip reinforcement is probably unnecessary and may add stiffness you don't want. But if you're logging serious days on the mountain, it can be the difference between gloves that blow out in February and gloves that survive the whole season.